there are lots of forums about specific sites to get music from, and most of the sites i know i found here, but I think it would help to have a thread for all links to site with lots of music.
DatPiff :: The Authority in Free Mixtapes - lots of mixtapes, nuff said
Motumbo's Sharing Time - really well run blogspot site with music. lots of harder to find hip-hop CDs. pretty sure this is the one run by a newschooler
True Hip Hop Spot - also very well done. similar to motumbo's. variety of hip-hop CDs. not quite as good, but still good
Rapsta's Music - also has a variety of hip-hop
Underground HipHop Album Collection Blog - variety of hip-hop CDs, including alot of classic hip-hop. Lots of music
Hot Hip Hop Albums - also has lots of hip-hop CDs. contains some of the more popular artists as well as some obscure ones.
SteezePod - another good site. normally good for a few single songs. has reggae, as well as some rap and rock single songs.
These are the ones i have on this computer. if i find more I'll post them
post your music links if you have some, any genre is good, mine just happen to be mainly hip-hop.
I hope this helps you out