http://www.mashup-charts.com/?ranking=30
This one is great for all the mainstream stuff mixed with rock, retro, hip hop and rap. All are video too. Tons of good ones


http://goodblimey.com/tunes/
This is a player that has 2800 songs, but you need to be more selective, they are so eeasy to download though, unlike the video links.

http://www.mashuptown.com/
This one is my home and has it all.