Links worth exploring.
http://www.fusionmanagement.com/overview.htm - This is a link to a management company in Burlington Ontario.
http://www.audiofind.com -This is a great resource for finding mp3 files, legitimate and non-legitimate.
http://www.geocities.com/SunsetStrip/Disco/9482/ - If you're working with samples or you're a DJ looking to remix, try this acapella site, it's full of acapella mp3s.