This is not mostly hip hop, but you’ll love it anyways. It’s a list of NME’s top 100 bands to watch out for in 2012, and they’ve linked to soundcloud so you can hear a track from each of them. This will keep you busy for DAYS.
The only one I recognize off the top of my head is 212 by Azealia Banks. Vulgar, but still blowing up the charts.