I'm sure its been said quite a few times, but the Official Google Blog is the most definitive, best blog there is.
Official Google Blog
In addition to the above link, I'm a big fan of the Google Chrome Fans page for tips and news and stuff.
Google Chrome Tips
And in general, I like to read Matt Cutts' blog about the Google Search algorithm. He details some of the inner workings, and often has quite a few great tips. Sorry if anyone's posted this already.
Matt Cutts