I believe I have heard of people converting racing seats from cars into chairs. I know these seats fit like a glove and are very comfy, and I bet would make a great computer chair provided you mount them to something (perhaps the bottom end of a regular computer chair).
Sparco makes very good seats though at premium. Many other make seats at a lower price as well (not sure on comfort/quality).
I found this site that seems to have reasonably priced seats.
http://www.airdynamicracing.com/shop...html?cat=seats
Anyhow just another idea.
-Brian
(Seatbelts not included)