I don't even remember how I stumbled upon this site, but I thought I'd share it with you as I've already found it invaluable.
The fine folks at Google (who, I'm pretty sure, are slowly taking over the world) have created a Blog Search tool. Whatever you're interested in, type it into the search field and voila! You now have a bunch of blogs writing about that very subject. Genius.
I'm putting a permanent link on the left-hand toolbar, just in case you decide you need it later.