I have an extensive set of blogs I check on a semi-regular basis; on top of that, books, magazines (i.e. Wire), recommendations from friends, stuff from movie soundtracks even. My problem right now (and it's been my problem for years) is that I find more great stuff than I have time to listen to. It's endless.
Anyway, a few sites I check:
factmag.com - Fantastic reporting on alternative stuff, particularly electronic, British music, and British electronic music. Great series of mixes, too.
The Quietus - Same as above.
20jazzfunkgreats - Nice, constantly updated blog, focusing on a lot of indie electronica
residentadvisor.net - Good-ish coverage of electronic dance music
And blissblog (i.e. blissout.blogspot.com), which is the official blog of Simon Reynolds, currently my favorite music journalist around, chock-full of interesting stuff.
And for all the badmouthing it gets, I still find cool stuff on Pitchfork, especially their columns. First time I heard of Isaac Hayes, now my favorite soul singer, was when Pitchfork raved about his reissue of Hot Buttered Soul, for instance.