If you type more than a few hours per day, check out a mechanical or hybrid (Topre) keyboard. Your wrists will thank you.
geekhack.org is a good resource.
To make a comparison, it's like going from a Toyota Yaris to a BMW 3 series, once you taste it, it's hard to go back. They're quality long-lasting keyboard that will be with you for many years to come, absolutely worth the hundreds of dollars. They will put to shame everything else. If only they came in ergonomic, that'd be amazing. I think there's only one single model in Japan and it's going to cost around $500-600 to import. Also, if laptops started to use Topre, that would be killer, even though they'd get much fatter. I'm tired of carrying my keyboard with me in the bag :)
That said, there were plenty of mechs in the nominees, they just didn't get enough votes to make the top five. Personally, I love them, but majority rules.
I currently use a "Logitech Illuminated Ultrathin Keyboard" and love it. But maybe I'm a freak, my wrists/hands feel a lot better using thin, laptop style keys rather than big clunky mechanicals.
Kinesis makes an ergo keyboard with Cherry keyswitches: http://www.kinesis-ergo.com/advantage.htm