If you've got a Flickr account then there's a lovely little online application called Dumpr which allows you to modify your photos, create reflections and make your own jigsaw puzzles from them.
My favourite tool is the photo gallery. This allows you to set your image in any one of four museum settings. Howevever my question is this: why aren't brands facilitating this kind of thing? Sony, Kodak, anyone in fact could get in on the act and provide me with this kind of functionality. The popularity of Flickr has made it a global site so any useful plugin will be lauded.