The Fader

http://www.thefader.com/

Truthfully, between this and Nahright, you can find 95% of the new music I pick up for DJing. While I haven't actually bought an issue of The Fader since I got the Cam'ron issue around the time Purple Haze came out, the blog is a great source of new music, especially hip hop and dancehall. They rarely post anything that they don't emphatically like, and are really into finding new artists, so it makes finding good pop music that much easier.