Nathan Harrington amended the GNOME Desktop Manager to include keystroke dynamics in the user verification process. When the user enters their username, the timings between key press events are measured and compared against a stored pattern. The theory is that there is a significant difference in timings for words typed by different individuals, so the way a username is entered provides a bit of extra “fingerprint” information that can be used to help authenticate a user.
I’m not sure how immediately useful this will be, since this particular example won’t affect other login methods, such as an ssh session. Nevertheless, the idea is pretty cool and the code is all there for you to monkey around with.