If you're a Flickr user, you might be unaware there's a whole world of tools that take advantage of Flickr's API to let you tweak and repurpose your shots. This morning I've been enjoying BigHugeLabs, a site that's home to about 40 tools that let you play with Flickr photos--yours and everyone else's. Several provide simple ways to add text, or a filter to your photo. Others dig deep into the heart of service to let you turn your photos into desk kitsch and conversation starters. I've picked five of my favorites.