Here comes my 100th Post.

You can submit your website and sitemap to Google, MSN and Yahoo. Now MSN is also supporting external sitemaps.

1. Google Webmaster Tools You need one Google Account for this

2. Yahoo Site Explorer You need a Yahoo account for this

3. MSN Webmaster Tools You need a Windows Live account (MSN Hotmail, MSN Messenger, or Passport account) to use this

Remember to use Robots in your site, since that will be an added advantage

Here is my Robots file content

user-agent: *
Disallow: /App_Code/
sitemap: http://geekiest.net/sitemap.axd

you can even save it with a content

sitemap: http://geekiest.net/sitemap.axd

For the MSN, you can ping MSN with updates to your sitemap using their Ping URL  Read it More from MSN Blog, MSN Support Cross-Domain Sitemaps

And if you are using Blogengine.net, you have a compatible sitemap (you van see my site map here http://yourwebsite/sitemap.axd, see mine sitemap). And for the ping service, Mads Kristensen  wrote one extension for this. You can read and download the extension from his website here