As far as Flickr viewers go, there's no other that comes close in coolness than Tag Galaxy. The rough idea is that each tag is a planet (or satellite) and selecting multiple tags will eventually lead you to the pictures you wanna see. It's neat, and extremely well done.
I'm a huge fan of data visualization and unique interfaces (which I've probably mentioned before), so when I saw The Whale Hunt, my jaw dropped. Not only is it extremely innovative in the way it presents the story, it's also a great example of photography as documentary, or simply put, photojournalism.
Since today seems to be all about flickr toys, there's no reaon not to mention flickrvision, which is a (some-what) live view of flickr, viewed on a map. Flickrvision takes advantage of the geotagging feature found in Flickr.
