I'm going to "officially" endorse a product that I use, and love to use: The Kinesis Freestyle USB Keyboard is hands-down the best keyboard I've ever used. I've had the keyboard for about 6 months now and I'm 95% satisfied with it.
There are two things I like most about the keyboard:
1) Ultra-low force keys. The keys on the Freestyle are really easy to depress, but they still have a lot of spring to them and the perfect throw distance.
2) Low profile. There aren't that many adjustable ergonomic keyboards available that are low profile. I have a hard time typing without resting my forearms on my desk, and a low profile keyboard allows me to do that without bending my wrists back too much.
There's only one thing I don't like about the keyboard: The position of the Windows key. (I hate the Windows key. I don't know why, I just do. I wish it wasn't on any keyboard.) I wish the key was more off to the side, because I find myself hitting the edge of the Windows key when I'm trying to hit the Alt or Ctrl keys. If I could reprogram the keyboard to make the Windows key a second Ctrl key I'd be 100% satisfied with it.
A note to Kinesis: I almost didn't buy your keyboard because of this stupid ad you put on YouTube. In it you make fun of the Key Ovation GoldTouch Keyboard. The GoldTouch is my third favorite keyboard*, and I thought it was highly unprofessional of you to trash your competitor in that fashion. What did they do to deserve that? Did the GoldTouch team noogie you at the ergonomic products convention last year or something?
* What's my second favorite keyboard? The keyboard on the Aluminum 12" PowerBook G4!