You're looking at the Cree 1W UV X-lamp 7090. I've made a few lights with them. They are quite a bit stronger and more capable of throwing than the 5mm UV leds I've played with when you put them in a deep reflector. The wavelength around 390-395nm is low enough to fluouresce lots of things, but still has a bit of visible purple to it. Yellow UV safety glasses help filter that out (and keep you safe).
When you consider UV lights, you must know that when dealing with low wavelenghts, some things only fluouresce over a very narrow range of wavelenghts. There are somethings you won't see with this LED which you would with a lower wavelength LED. There are somethings you must get really close to with other LEDs to get the same effect you can with this from afar. It's good to consider what you want to react and there is a website--I think maybe it's the work of xenopus, but I don't remember off hand--that lists what each wavelenght is best for. If you find that website, I'd recommend it.
I like this LED because of it's output and focusability. I like being able to focus the light and charge up all my glow in the dark stuff around the room in the middle of the night before getting out of bed.
I would caution you to consider your market if you want to buy these in bulk, because they don't seem like something for your average Joe--or even your average CPF Joe. Some people seem quite scared of them. If you want to get a few to try out--LEDite seems to have a good price, and I might have a few too.