a few good things to check out if you like mashups:
Downloads : chrismacro.com
dude does awesome reggae/hip hop mashups
Girl Talk ? Free listening, videos, concerts, stats, & pictures at Last.fm
a bit played out now, but still good fun when bombing down the hill
if you're into metal and hard electronic music then this guys mixes are for you!
2004.08.22 - Essential Mix - Scratch Perverts by +dB on SoundCloud - Create, record and share your sounds for free
one of my favorite mixes of all time; all sorts of music thrown together live by 3 dj's and 6 turntables!