Tag Galaxy is a rather weird but interesting way of browsing through Flickr images – probably more for casual browsing than a specific search. You start off with a tag on a topic (which becomes your ‘central planet’) while other related tags appear in your galaxy. You can then click on those related tags and browse photos with both the original tag and the subsequent tag(s) (top picture).
And eventually, when you really do want to look at those photos, you can click on the planet and photos will ‘land’ on the planet (2nd picture).
I thought the visual/cognitive link between the two was a tad too literal and forced, but an interesting interface nonetheless for exploring images in a (pseudo)-3D space (yeah, space).