Doesn't it just ruin your day when you're skulking around some high security area and you need to get into a secure room that is access controlled via a fingerprint scanner? I know it's ruined many a day for me.

Never fear, for here is step by step guide on how to defeat those dastardly devices, but be sure to have a supply of Jell-O at your disposal. Here is one guide, and here is another. Here is more background and here is the technical paper that started it all. Here is a page that discusses the legal implications.