Recs.
Updated
The Kinesis Advantage2 is a uniquely-shaped ergonomic keyboard that is the best at preventing injuries associated with prolonged, incorrect hand posture and finger strain. The key layout is designed so that it can be used in the most optimal way possible, with a set of keys assigned to each finger. All these factors combine to make the Advantage2 the best option for enjoyable, rested and productive programming.
SpecsUpdate
Pros
Pro Tweaked layout that saves your hands
This keyboard has numerous ergonomic advantages over a keyboard with a standard layout. Some of them are obvious and some are subtle, but they are synergistic and result in a typing experience that places far less stress on the hands. Learning a tweaked keyboard layout is a small price to pay to avoid RSI (repetitive strain injury).
Pro Clusters of keys under each thumb means less reaching
Having multiple keys under the thumbs lets you keep the rest of your hands still, and helps prevent reaching. For example, the backspace key on a regular keyboard is way in the top right corner, while on the Kinesis keyboard it's under the left thumb. So, to hit the backspace button you just need to move your thumb while on regular keyboards you need to move your whole right hand and stretch your pinky to reach it.