I'd like to point out some of the best people that have been named in this thread (aesop rock, sage francis, talib kweli) and some that havent (atmosphere, pos, dynospectrum, el-p, mr lif) isn't exactly rap. It's hip hop. Rap, especially as of recently, is nothing more than hype shit about gangbanging. That's why everyones dick is so hard over lil wayne, young jeezy, dipset, blah blah blah. If it's actual rap you're interested in, go back to wutang clan, murder ma$e, shyne, tribe called quest, nwa, nas, digable planets, geto boys, slick rick blah blah.
Oh, and hip hop lyrics actually carry meaning.