Recs.
Updated
The Happy Hacking Keyboard Professional 2 is a keyboard with a reputation, and it lives up to it. The HHKBs originated from a collaboration between PFU and Dr. Eiiti Wada, a Japanese computer scientist who was unhappy with existing solutions. His research led to the current compact layout. As the name hints, it was designed with programmers in mind, particularly emacs and vims users.
SpecsUpdate
Pros
Pro Easily programmable and highly modifiable
This keyboard comes with the standard DIP switches to modify key behavior, but you can also completly swap out the controller board or even fork the TMK firmware to make your own keybindings in the firmware. Also available is the TMK controller board custom made for HHKB users.
Pro Designed to keep you in home row
This keyboard was designed to make life easier for programmers. The layout allows fingers to stay in the home row most of the time. It's achieved by several adjustments. For example, the Control key is placed where the Caps Lock traditionally is, because it's used more often.