BatteryJunction.com has a great selection of handheld Ultra-Violet lights!
Ultraviolet or black lights as they are also known are used for a wide variety of applications. The ultraviolet radiation itself is invisible to the human eye, but illuminating certain materials with UV radiation prompts the visible effects of fluorescence and phosphorescence. Black light testing is commonly used to authenticate antiques, banknotes, credit cards, and ID's. Extensively used in non-destructive testing; cracks and other artifacts can easily be detected. UV light is also good for detecting pet messes such as urine, vomit and other substances that are not always visible to the naked eye. Also good for mineral lighting and identification, adhesive curing, glass inspection and repair, etc.