[EvanK]

Not exactly what you're asking, but I took a chance on replacing my chair entirely with an inflatable exercise ball, and I'm quite happy with the result. It took a week or so to get used to, but my balance has somewhat improved and my lowe back actually seems a little stronger. I'm also putting the money I saved on a chair into buying an adjustable height desk so I can stand & work when I get tired of bouncing on said ball.

[mlLK]

What kind of desks are you looking into?

[EvanK]

Thinking of getting a GeekDesk. You can buy just the frame, then find your own desk top piece (and a hollow-core door from home depot will work just fine)

[mattmichielsen]

I think this winter I'm going to build my own version of the GeekDesk. I'll put it on instructables.com or whatever and document it. I'd start today, but I have too many other house projects to do while it is still warm out.