Howard Dean's webmaster, Garrett Graff - the guy that helped Dean raise millions in campaign contributions on the internet - has a blog called Fishbowl DC. Pretty impressive site, definitely worth stealing ideas from.
Also check out Ana Marie Cox, formerly an editor at Mother Jones magazine, at Wonkette.com. Ana (Ahh-nah) is a goddess incarnate, I have a huge crush on her.
John Stanton's CongressDaily is updated twice daily with the ongoings on Capital Hill.
Two of the best blogs are American Prospect(Matthew Yglesias is one of many contributors) and Daily Kos. Daily Kos is one of the first blogs ever created, and has gotten pretty cool with the addition of daily diaries of congressmen and senators. The guy who started Daily Kos is Marcus Moulitas. He's in his early 30's, one-smart-dude.
Last but not least is NRDC Action Fund, incredibly well written, thought provoking and has guest bloggers.