Groovefish will allow the most excellent Grooveshark music streaming service to be used on a Windows Mobile 6.x device.

Changes:

Big rewrite of some of the code – should fix some problems, may cause others!
Sporadic crash on exit should now be fixed.
Searches can now be cancelled.
Fixes a crash that sometimes occurred when scrolling the search results.
… QVGA compatibility!

http://forum.xda-developers.com/showthread.php?t=561374