Since the last entry to this node in March 2003, PFU has introduced a new line, the Happy Hacking Keyboard Professional. You'll either love or hate this keyboard, as clichéd as that may be. On one side there are people saying that it feels like typing on heavenly clouds and they might as well have been born with this keyboard in their hands, the layout is so intuitive. On the other side, there are people who complain about the lack of dedicated arrow keys and don't understand who in their right mind would use Topres instead of buckling springs or Cherry MX switches. Those who could take it or leave it are few and far between.
While the Lite models use the rubber dome over membrane switch that you'd be used to encountering in any given keyboard, the Professional versions use Topre capacitive switches. The Topre switch is made of a rubber dome, which collapses to provide the snappy feeling that lets you know you've done what you were trying to do without having to visually process the result, and a conical spring that effects actuation. As the spring is compressed under the dome, it changes the capacitance of a capacitive sensor on the PCB. Once this change is significant enough, right after the peak of resistance from the dome, the keystroke is registered. A not insignificant amount of space lies between that point and the bottom; it's theoretically possible to avoid bottoming out the keys, but this is difficult as there's a dip in resistance after actuation. Topres have neither the noise nor the 60-80 cN resistance of the buckling spring switch. The bump itself is silent—any noise comes from the keys bottoming out or snapping up when released—and is not unlike the feeling of a piano key giving way. The switches on the HHKB require 45 cN to actuate; Topre manufactures switches with actuation forces from 30 to 55 cN.
There is some disagreement over whether a keyboard with Topres counts as mechanical. While Topres use rubber domes, they also contain springs, have a crisp rather than a mushy feeling, and actuate mid-stroke instead of as near to the bottom as makes no odds. This has led some to call it semi-mechanical.
You can get the HHKB Professional 2 with blank or printed keycaps. If you want to look cool from a distance but need to cheat on occasion, try the subtle black on charcoal grey. The keys on this board go right where they belong: backspace is above enter, and control goes where the caps lock normally would. Caps lock is available in a function layer on the tab key for those heathens who may happen upon this glorious instrument. Escape is nicely within reach in the upper left-hand corner. The F-keys share a row with the numbers and can be pressed using one hand, albeit with some acrobatics, as one finger must be on the Fn key. This model has six DIP switches that define how various keys behave.
This keyboard is a serious commitment at US$250-300. If you really have some money burning through your pocket, there's a Type "S" (for Silencing) for $400.
May you have good feeling of oneness with cup rubber.
http://deskthority.net/wiki/Topre_switch
Inside a Topre switch
Topre force curve graph
HHKB Professional 2 layout
DIP switch and mode charts