Recently I built myself an Atreus keyboard from a kit. You can buy the kit from here: http://atreus.technomancy.us/
The build process was pretty fun although my soldering skills aren't great.
I use dvorak and technomancy suggests using the softdvorak mapping which only has some slight changes from qwerty. He then uses the OS remapping to dvorak like with most other keyboards. This does work though I've made a hardwareDvorak mapping aswell so that you can just plug and play the keyboard as dvorak without needing to do any mapping at the os level.
I still haven't switched to this as my daily usage keyboard mainly because I haven't remapped my window management hotkeys for BetterSnapTool in OSX just yet. I'd like to be able to have 2 sets of hotkeys for the same actions so I might have to swap to a different window manager like Slate. I'm also finding it a little weird getting used to straight columns. I think it makes a lot more sense to have straight columns but my fingers have years of muscle memory to overcome still.