Flickrleech allows you to pull up massive screenfuls of thumnails across interestingness, username, user ID, photoset, group pool, search, etc. You can keep it loaded in the background while you click through on great shots and view, fav, comment etc.
If you use Flickr. You must check this one out. This toy will easily triple my productivity in viewing shots on Flickr. Amazing.
Really blown away.
Update: Flickr’s Stewart Butterfield says cool, but horrible at the same time.