Technorati calls itself the authority on what's going on in the world of weblogs. Be that as it may, I use it quite frequently to search for differing topics if Google doesn't come up with what I'm looking for.
A feature I've been using more recently, is Technorati's ability to feed me
posts which are tagged with a certain keyword. Just add the URL
http://feeds.technorati.com/feed/posts/tag/google to your feed reader,
exchanging google for whatever tag you are interested in.
Apropos Technorati tags: see also an introduction to Technorati Tags.