One of my favoritre sites to visit is Pizdaus. It has some of the most beautiful and interesting pictures on it. And it’s being constantly updated. I only use a few pictures from the site for Bits & Pieces (usually the funnier ones), but I try to visit it every day and am continually amazed at the breathtaking photograpy I find there. If you’ve never been there I highly recommend it.
Another similar sight I’ve found is Flickriver. It is like a flowing river or stream of amazing photos posted on Flikr. You can sort by any subject too. I’m sure there are more sites like these.. or even better, but I just wanted to pass these two onto you.