I both work and play on computers. I sit in the same chair averaging about 14 to 16 hours a day. I've been sitting this long every day for about 15 years and the trouble it causes is no-longer subtle. I even bought a really nice (BodyBilt) chair to try and help my back but after a few years it hasn't helped all that much.
One of the main ways I've been able to get relief is by alternating between sitting at a desktop, and using a laptop in bed propped up with my elbows. This position tends to reverse the bulging disk issues that sitting causes, but it is a hard position to maintain for more than a few minutes without getting a stiff neck.
I began thinking out of the box recently and I've built myself a new "chair" based on maintaining the position of using a laptop in bed more comfortably, and at my desktop workstation. I have a prototype I use built out of lumber and spare parts I had around (I'm actually using it now). It keeps me at a slight incline and supports my feet to help keep the spine compressed which helps keep the bulging disks in check, and it works quite well. My arms rest on my normal desk and use my normal keyboard and mouse. I'm still working on a way to support the head comfortably, but any company looking to productize such a device would probably have an easy time with that problem. I'd really like to see some work in this area, since I suspect this is ergonomically far superior to sitting, but I fear it's too radical for companies to embrace.
The other option I'm exploring is a treadmill desk (I ordered one a few days ago). I have a standing desk, but standing still is just too uncomfortable for me to do for any appreciable amount of time. I'm hoping the motion of a treadmill desk will allow me to work longer without pain, as well as giving me some exercise.
Another thing I can recommend to anyone who has occasional back trouble is a Nada Chair Back-up. It's a simple little device for pulling your spine into position by strapping it to your knees. It definitely helps reverse the uneven pressure on your spine caused by sitting, and it has rescued me from back trouble many times. It's a cheap simple device, and I find it helps a lot when things get bad, but it's hard to wear it enough to keep things from getting bad in the first place.