Lensbabies are selective focus SLR lenses that have a "sweet spot" surrounded by a gradual blur. The sweet spot is moved by bending the lens. Check out lensbabies.com for more info, galleries and list of products available.
I have the Original Lensbaby lens and it is awesome. It has opened my eyes to a whole new way of seeing the world and my photography. If you are looking to try something new and interesting just by changing your lens; try a lensbaby.