http://backintheyay.blogspot.com/
http://djggoblin.blogspot.com/
http://hiphopruckus.blogspot.com/
http://mixtape-master.blogspot.com/
http://uni-verse-all-music.blogspot.com/
http://www.free-mixtapes.com/
http://www.datpiff.com
http://2dopeboyz.com/
http://da-underground-kingz.blogspot.com/
http://www.hhworlds.com/forum/index.php
http://www.bayontop.com
http://www.realraptalk.com
http://hear-it-first.net/
http://hotnewhiphop.com/
http://mzhiphop.com/
All these sites contain more music than you will be able to fit on your harddrive, and are updated frequently, they will stay up, as a reference guide, but i cannot go through it all.