The SafeType Keyboard
Do you understand how to use it? The idea is that your hands and arms shall be in a more relaxed position while working with the SafeType compared to a traditional keyboard. However, if you have a low tolerance for frustration (and learning to type in a new manner can be frustrating) then your best bet is to stay flat and stick with a keyboard that's a little more Common.
3D Ergonomic Keyboard
Getting used to this keyboard isn't something you'll do in 10 minutes or so - it will take a while for sure. But if you have medical problems with your hands, this might be a good choice since it's a very ergonomic keyboard. It looks very weird though!
The wrist keyboard
This one might be useful if you're in the need to type stuff while doing practical work in tough climates - but if you would wear this keyboard at the office, you might be considered a bit geeky.
This keyboard has the same measurements as a standard 102-key keyboard, but there's a big difference. You can roll this one up and put it in your pocket. Nice; isn't it?