I have just added few online malayalam radios. Check the pages section or it is here

1. Asianet malayam Radio Online

2. Joy Alukkas Malayalam Radio Online

3. Deepika Malayalam Radio Online

4. Radio india Malayalam Radio Online

5. Hit 96.7 FM malayalam Radio Online

Will enter the details of how you can hear this using Winamp or media player,soon ( may be tomorrow ;) )