Well, I'm pretty involved w/ hip hop as my background is in promotions, but in hip hop you basically have 2 categories
1) "Real hip hop" heads - you want to appeal to their pretentiousness. Find something that helps them feel like they're "supporting the struggle," helping spread "truth," etc. I would imagine Obama type shit would do well with them. Also, I've not used the "survey" technique for CPA, but from what I gather, you could probably make a killing off of these people with it because they are SOOO opinionated.
"Is KRS-one out of his mind?! Yes - No. Win a free ipod."
"Biggie or Tupac"
"Nas or Jay-Z"
etc.
Those are your "real hip hop heads"
2) If by "hip hop" blog you mean mainstream urban music then go with what everyone here has said, grillz, bling, ring tones, mp3s, etc. That shit simply works. The free iPod would probably do well too.
Let me just put it to you this way, kids in the hood still go to Walgreens and buy CD players, yahdig? ... If that didn't give you some physchographic insights you may want to choose a different market
p.s. @10k uniques/mo, you could probably get into some decent vertical ad networks. Just a thought.