These Key Catcher things are really small and really sneaky, aren’t they? From $89.99.

‘This is a device that can be connected to a keyboard to record all keystrokes. It has a changeable password, keyword search, enable/disable option, and stores URLs. Records more than 130,000 keystrokes and does not require any software. Monitor unauthorized access to your computer or your network. Use it to troubleshoot or make fixes by tracing back through a users command sequence.’