If you've ever used the old
Apple ADB Extended and Extended II keyboards, you might be interesting in the keyboard listed below. I loved the old ADB extended keyboard--I think it came with an Apple Quadra. I moved that keyboard from Mac to Mac until USB popped up and ruined things. I guess I could have bought an adapter for it, but by that time the keyboard was starting to show some signs of age.
The Matias Tactile Pro Keyboard is built from the same premium keyswitch technology that Apple used in its original Apple Extended Keyboard, widely viewed as the best keyboard Apple ever made.
http://matias.ca/tactilepro3/index.php#
During my search for a better keyboard, I also found many fans of the
IBM model M keyboard. It is still being produced by a former IBM employee who started Unicomp Keyboards to produce keyboards that use the buckling spring switches.
http://pckeyboards.stores.yahoo.net/keyboards.html#
I picked up a used GoldTouch GTU-0033 keyboard (see:
http://www.goldtouch.com/ ) that I've been testing. Overall, I like the keyboard. The keys require very little effort to engage. One problem has cropped up. When my G4 goes to sleep it takes the keyboard with it. The only way to get the keyboard back in action is to wake the computer, unplug the keyboard and plug it in again. (NOTE: I'm using the PC version of this keyboard on a Mac, which could be the cause of this sleep problem.)
Steve