Flickr is fun. And its public API makes it easy for folks to make some really neat interfaces to its pictures and its community. Like Spell with Flickr – just type in a word or phrase and you get back pix from flickr that spell out your word/phrase. Or Tagnautica, whic lets you just type in a tag and it finds related tags from Flickr in a most zen-like fashion. The Colr Pikr lets you interactively try out different colors and find Flickr images that match your selection.