Originally Posted by karjor
I have used a balans-type (kneeling) chair for over 15 years. Mine is has rollers and is heigh adjustable. I can sit in it for hours at the computer, and my particular flavor of back problem does not like sitting in a regular chair for too long. This is not for everyone - can be awkward to get in and out of until you are used to it, but it works well for me. If you have a relax the back type store, I'd recommend checking one out to see if it suits you. Kneeling Chair With Memory Foam | Relax The Back
They come in many options - I'd recommend the memory foam version.
I had this type of chair some years ago and it is very comfy, except I have bad knees. It seemed to make me bear most of my weight on my knees and shins while sitting and after awhile my knees would be killing me. Just something to keep in mind when considering this type of chair.