I have always been a fan of the old style IBM keyboards with the 'noisy' key clicks. I have several that I have collected over the years, and have hooked some friends up with them. In a pinch you can buy one from the manufacturer that has taken over maintaining and creating new ones. These are used heavily in POS (Point of Sales) applications. Its a nice keyboard.

http://www.pckeyboard.com/ibmlist.html