[jimmahoney]

I'm typing from an Ikea Marcus which is my home office chair.

While I agree that the Aeron is great (and have one at work that I use regularly), the Marcus fit in my budget ($200 for the Marcus vs $800+ for a new Aeron) and is perfectly reasonable. I usually leave it in the locked forward typing position.

For twelve hour stints, I stand for part of the time (my desk will move up to standing height).

I tried an exercise ball - didn't work for me.

[djaychela]

Another vote for the Markus here - I've had an adult lifetime of back problems due to being attacked when I was 19 (I'm 45), and this is the first chair I've found in years that I can sit in and work for more than half an hour without problems - in fact, I bought it the weekend before I needed to do several straight 12 hour days working on a project with a tight deadline and instead of being crippled at the end of it I felt OK. The seat-to-floor height is just right for me, and it offers just the right amount of support. Hopefully I won't stain it like the other poster here!

[vosper]

I liked my Marcus a lot, and I thought it looked great, too. Unfortunately I stained the fabric and found it impossible to get it out, so I'm not sure if I'd buy one again.