My favorite keyboards;

Can't beat the keyclick, or the beeper!

Sun Type 3
(typed on this keyboard, hitched to a slightly more modern Sun IPX)

The PFU Happy Hacking keyboard has almost the exact same layout as the Sun Type 3. Their web site also has an excellent collection of keyboard layouts.

My other favorites are the VT100 (great for use on the lap), the Apple M0116, and the PC/XT keyboard (great tactile feedback).