I got a pair of the "underwater" blue lights, which are unassuming little guys when you see them in person -- but they do a remarkable job of recreating an underwater ambience (rather like what you would see on the bottom or sides of a swimming pool, if you yourself were underwater).
It's a very sophisticated effect, and particularly remarkable given how inexpensive these are. I'm using them as a background effect with laser holiday images layered over -- couldn't be happier :)

Love these lights. Used them for an art installation at a local festival highlighting sea life, and they were gorgeous. Super easy to use, just plug in and go!