Logitech created this funky Wave keyboard sometimes in 2009.
Logitech got this Wave keyboard. I never actually used it, but only tried it out in stores. Am not quite sure such wave design is ergonomic. The keys are not split. Nor are they curved much like a smile such as with Microsoft's Comfort Curve keyboard. It just dents up and down, i suppose because your index fingers are longer so it dents down there.
However, Amazon seems to have good reviews. Such matters really needs to be personally tested out and used for a week to judge well. But just on principle and experience, i say this: If you don't mind straight keyboard, this might be a improvement over flat surface. But if you have any form of RSI, or must use split ergo keyboard, this keyboard isn't good.
I went to local electronics shop and tested out this keyboard. It's SH�T.
You know how some rubber dome key is such that sometimes when you try to press a key, it stuck and won't go down, due to the friction of the housing. The Wave keyboard's keys are like that.
If you really want ergonomic keyboard, i suggest:
If you don't care for split setup, then i recommend keyboard with mechanical key switch: