This is from Wikipedia

2008

• Kidaro , Ramat Gan, Israel - March 12th, 2008, Enterprise Desktop Virtualization, $100M (speculated)
• YaData , Raanana, Israel - February 27th, 2008, micro-segment advertising , $30M
• Danger, Inc., Palo Alto, California - February 11th, 2008
• Caligari, Mountain View, CA - February 6, 2008 - 3-D modeling and animation software
• Calista Technologies, San Jose, California - January 21, 2008 - Desktop Virtualization Solutions
• Fast Search & Transfer, Oslo, Norway. - January 8, 2008. $1.3 billion - Enterprise Search Company

2007

• Multimap.com, London, UK - December 12, 2007 - Location-based services.
• Global Care Solutions, Bangkok Thailand - October 29, 2007 - Health care software vendor.[
• Jellyfish.com, Middleton, Wisconsin, USA - October 2007 - Online discount shopping site.
• Parlano, Chicago, IL, USA - August 2007 - maker of MindAlign - a leading application for enterprise group chat that enables people to carry on topic-specific, multiparty instant messaging discussions that persist over time. Parlano’s group chat functionality is expected to be added as a new feature of Microsoft® Office Communications Server and Microsoft Office Communicator
• AdEcn, Santa Barbara, CA, USA - July 2007 - Advertising Exchange Platform Company where advertising networks can come together for buying and selling display advertising.
• Stratature, Atlanta, USA - June 2007 - Unified Master Data Management Solution which will become part of Microsoft's Business Intelligence efforts.
• Dundas, Toronto, Canada - June 2007 - Charting controls for SQL Server. People and technology acquisition, but not the whole company.
• Engyro Cincinnati, OH, USA - June 2007 - Interoperability software for Systems Center and Operations Manager.
• aQuantive, Inc, Seattle, USA - May 2007 - Global digital marketing and advertising solutions. Microsoft's largest acquisition in history so far, valued at $6 billion.
• SoftArtisans OfficeWriter, Watertown, MA, USA - Reporting authoring in Microsoft Office. People and technology acquisition, but not the whole company.
• ScreenTonic SA, Paris, France - May 2007 - Mobile advertising solutions
• devBiz Business Solutions, Izmir, Turkey - March 2007 - Web interface for Microsoft Team Foundation Server
• Tellme Networks, Inc, California, USA - March 2007 - Voice services, Estm. $750+ million
• Medstory, Inc, California, USA - February 2007 - Health care search technology
• Secured Dimensions, Israel - January 2007 - Secured Software Provisioning, $600,000.

2006

• Colloquis Inc. New York, New York and Sunnyvale, California - October 2006 [20] - Intelligent agents
• DesktopStandard Corporation, Portsmouth, New Hampshire - September 2006 [21] - Group policy-based enterprise desktop management
• Gteko, Ra’anana, Israel - September 2006 [22] - Networking and support software manufacturer
• Azzyxi, Washington - July 2006 [23]
• Winternals, Austin, Texas - July 2006 - System recover and data protection tools, Sysinternals freeware tools provider
• Softricity, Inc. Boston, Massachusetts, USA - July 2006, Application Virtualization and Application Streaming
• iView Multimedia, London, England - June 2006 - Digital Asset Management software for Macintosh and Windows
• Whale Communications - May 2006 - Firewall-Specialist, $75 million
• DeepMetrix Corporation, Quebec, Canada - May 2006 - Business intelligence solutions
• Massive Inc. - May 2006 - Ingame-Advertising
• AssetMetrix Corporation, Ontario, Canada - April 2006 - Asset-management and Business intelligence
• Lionhead Studios - April 2006 - Games Developer
• ProClarity - April 2006 - Business-Intelligence-Specialist
• Vexcel, Boulder, Colorado - March 2006 - Satellite Imaging
• Apptimum, Inc, Florida, USA - March 2006 - PC Settings/User State Migration Software
• StringBean Target, Maryland, USA - March 2006 - iSCSI SAN solutio
• Onfolio, Massacheussets, USA - March 2006 - Internet search and information management provider
• MotionBridge, Paris, France - February 2006 - Search technology for mobile operators & the mobile Internet
• DynaComm i:filter product from FutureSoft, Houston, Texas - February 2006 - Only the web filtering product

2005

• GeoTango, Toronto, Canada - December 23, 2005 - 3D mapping and visualization
• GeoTango UMT, New York, USA - December 2005 - Project & portfolio management software
• FolderShare, Austin, Texas - November 4, 2005 - Remote Access and Synchronization Software
• MediaStreams, Switzerland - November 3, 2005 - VoIP Software [34]
• Certain technologies from Unveil Technologies Inc., October 2005 - For Microsoft Speech Server
• Alacris, Ottawa, Canada - September 2005 - Identity and Access Management Solutions Provider Teleo - VoIP
• FrontBridge Inc., California - July 2005 - Email Protection Services
• MessageCast Inc. May 2005 - Automated alerting and messaging services
• Groove Networks Inc., Beverly, Massachusetts - March 10, 2005 - Collaboration software , $120 million
• ContentGuard (jointly acquired) - March 2005 - DRM technologies
• FRx Software Corporation - March 2005 - Financial analytic applications
• Sybari Software Inc., East Northport, New York - February 8, 2005 - Anti-virus, anti-spam, and content-filtering add-ons - between $163 million and $182 million
• Certain technology from En'tegrate Software LLC - February 2005 - Axapta-related technology

2004

• GIANT Company Software, Inc., New York City, New York - December 16, 2004 - Spyware protection, detection and removal tool
• Lookout Software LLC, Palo Alto, California – July 19, 2004 - E-mail and desktop search - $10 million
• Accounting products from Encore Business Solutions, Inc. - April 2004
• ActiveViews Inc. - April 2004 - Ad hoc reporting product

2003

• Creature House Ltd., Hong Kong – November 6, 2003 - Natural media drawing software
• RAV Antivirus technology from Romanian company GECAD - June 11, 2003
• PlaceWare Inc., Mountain View, California – May 1, 2003 - Online Web conferencing service - $200 million
• Connectix, San Mateo, California - February 2003 - Virtual PC and Virtual Server

2002

• Vicinity Corp., Palo Alto, California- October 2002 - Internet-based marketing infrastructure services - $105 million
• Rare Ltd., United Kingdom - September 29, 2002 - Video games - $375 million
• Sales Management Systems, USA - May 2002 - Provider of point-of-sale software.
• Navision Software A/S, Vedbaek, Denmark – May 21, 2002 - Business applications, ERP - $1.45 billion

2001

• iCommunicate, Alexandria, Virginia -- May, 2001 -- Business application for bCentral and later Microsoft CRM
• Ensemble Studios, Dallas, Texas- May 3, 2001 – Video games
• NCompass Labs Inc., Vancouver, British Columbia, Canada - April 30, 2001- Web content-management solutions - $36 million
• Great Plains Software Inc., Fargo, North Dakota - April, 2001 - Business applications, accounting - $1.4 billion
• Maximal Innovative Intelligence Ltd., Tel Aviv, Israel - February 2001 - Business Intelligence

2000

• Digital Anvil Inc., Austin, Texas - December 5, 2000 – Video games
• Pacific Microsonics Inc., Union City, California - September 18, 2000 - Digital music software
• MongoMusic, San Mateo, California - September 13, 2000 - Online service with advanced music-searching capabilities- $65 million
• NetGames USA, Overland Park, Kansas - July 12, 2000 - Scoring, matchmaking and other enhancements for retail and Web-based games
• Bungie Software Products Corp., Chicago, Illinois - June 19, 2000 - Action oriented computer and video games - Approx. $38 million
• Driveoff.Com, Littleton, Colorado - June 12, 2000 – Online car sales
• Peach Network LLC, Tel Aviv, Israel- February 29, 2000 - Enhanced television services for digital television

1999

• Entropic Research Laboratory Inc., Cambridge, UK and Washington DC - October 29, 1999 - Speech recognition software - $90 million
• Softway Systems Inc. San Francisco, California - September 17, 1999 – Customer interoperability solutions
• Visio Corp., Seattle, Washington - September 15, 1999 – Enterprise-wide business diagramming and technical drawing software - $1.4 billion
• STNC Enterprises, Suffolk, UK - July 21, 1999 - Internet access solutions for wireless products
• Sendit AB, Stockholm, Sweden - July 1, 1999 - Mobile Internet solutions - $130 million
• OmniBrowse Inc. Bellevue, Washington, - June 15, 1999 - Applications for wireless handheld devices - $400 million
• ShadowFactor Software Inc., Waterloo, Ontario, Canada - June 7, 1999 – Video games - $120 million
• Jump Networks Inc., Ithaca, New York - April 26, 1999 - Web-based calendar services
• Access Software Inc. Hialeah, Florida - April 19, 1999 - sports simulation software and adventure games
• CompareNet Inc., San Francisco, California - March 4, 1999 - Online comparison-shopping service
• Numinous Technology, Inc., Seattle, Washington – March 29, 1999 - Internet graphics, digital video management and traditional printing applications
• FASA Interactive Technologies, Chicago, Illinois – January 7, 1999 - Video game division of long-ailing board game and role-playing game vendor
• ZOOMIT Corp, Toronto - July 7, 1999 - meta-directory products

1998

• LinkExchange Inc., San Francisco, California - November 5, 1998 - advertising network - $250 million
• Valence Research Inc., Beaverton, Oregon - August 25, 1998 - Advanced clustering software
• MESA Group Inc., Newton, Massachusetts - April 28, 1998 - Messaging and applications migration products
• Firefly Network Inc., Cambridge, Massachusetts - April 9, 1998 - Personalization software - $40 million
• Flash Communications - February 23, 1998 - Messaging client/server product
• Compu-Global-Hyper-Mega-Net., - February 15, 1998 - Unspecified activities - $0 million

1997

• Vxtreme Inc., Sunnyvale, California - August 5, 1997 - Web Theater technology - $75 million
• LinkAge Software Inc. Toronto, Ontario, Canada - June 30, 1997 - Connectivity solutions for e-mail software - $30 million
• Cooper & Peters Inc., Boulder, Colorado - June 13, 1997 - Object-oriented user-interface frameworks and applications - $20 million
• Dimension X, San Francisco, California - May 7, 1997 - Multimedia technology
• WebTV Networks Inc. Mountain View, California- April 6, 1997 - Enhanced TV services using Internet and digital technologies - $425 million
• Intersé Corp., Huntington, West Virginia - March 4, 1997 - Software for analyzing user activity on World Wide Web sites
• Hotmail Corp., Sunnyvale, California, - January 3, 1997 - Webmail service - $395 million

1996

• NetCarta Corp., Scotts Valley, California - December 10, 1996 - Web-site management software - $20 million
• ResNova Software Inc., Huntington Beach, California - November 20, 1996 - Web server products
• eShop Inc., San Mateo, California - June 11, 1996 - Internet commerce software
• EXOS Inc., Woburn, Massachusetts - April 15, 1996 - Force feedback technology for game control devices
• Vermeer Technologies Inc, Cambridge, Massachusetts - January 16, 1996 - Visual, standards-based Web publishing tools - $130 million
• Colusa Software Inc., Berkeley, California - March 12, 1996 - Object-oriented programming software for the Internet

1995

• Bruce Artwick Organization Ltd., formerly subLOGIC Corporation, Champaign, Illinois, - December 12, 1995 - Entertainment software (Flight Simulator), 3-D graphics packages
• Blue Ribbon Soundworks Ltd, Atlanta, Georgia - October 16, 1995 - Interactive music software for games
• NextBase Inc. United Kingdom - January 30, 1995 - GIS and consumer route planning and map software sold under the names "AutoRoute", "Automap", "Streets and Trips"
• RenderMorphics Ltd. - February 23, 1995 - RealityLab software for 3d graphics, later rebadged by Microsoft as "Direct3D 3.0"

1994

• One Tree Software. - November 15, 1994 - Version Control software, SourceSafe
• Softimage Inc., Montreal, Quebec, Canada - June 28, 1994 - High-end 3-D animation software - sold later to Avid Technology Inc. on June 15, 1998

1992

• Fox Software, Perrysburg, Ohio – 1992 – Database software - $173 million

1991

• Consumers Software Inc., Vancouver, BC, Canada - April 1, 1991 - The Network Courier

1987

• Forethought Inc., Sunnyvale, California - August 3, 1987 - Presentation and graphics software

1986

• Dynamical Systems Research Ltd, Berkeley, California – 1986 - Multitasking operating system - $1.5 million[95]