I recently published a blog on how to scientifically interpret what different fingerprint patterns indicate in terms of personality traits.
You can check that blog out here: Intimate Science
A question came up about how to view fingerprints, so here is a demonstration of how to very simply view fingerprints with great contrast.
This makes for a great party trick and if you combine it with a little scientific interpretation as in the blog linked above, you should get your 15 minutes of fame.
I was considering going into some detail about why the light is doing what it does in this video, but it gets a little involved with frustrated total internal reflection, index of refraction and light propagation concepts, so the easier thing is just to play around with different lighting angles a see what happens, it couldn't be less expensive to experiment with. One hint is to note that wherever my finger is not touching the glass, the glass looks dark - there is no reflection there.
Have fun with this and check out the Intimate Science link for an interesting application.