Back in the mid 90's, I hypothesised that everybody had a distinctive pattern to the way that they typed specific words. The pattern that I typed my password was predictable and consistant. Meaning that if my password was "toyota", the time it took me to type the letters "t" and "o" was relatively static, but would be completely different from someone else typing the same word. So my idea was to build a product that added keyboard recoginition as another layer of authentication. With this technique, I could tell you my password and unless you were a proficient percussionist, you wouldn't be able to autheniticate with my credentials. I did some prototypes, writing a Gina dll and tested with a few people, but before I took the time to refine it, this company published their implementation.

Today I read of a new technique (link) that uses a microphone to listen to someone typing. Apparently, by recording the sound of someone typing, they are able to reconstruct the keys that were pressed. A new reason to be paranoid...