I use some chairs that were in use by a local supermarket and which got thrown out due changes in the interior. It may sound silly, but keep in mind that the people behind the counter need to set for long periods of time just like your average hacker. These chairs can be lifted to the point where I (my height: 1.96m) cannot put my feet straight on the ground anymore, have several 'joints' to setup and are the most comfy chairs I've ever used. I don't know the brand, so you probably need to ask at your local supermarket. Best of all I got mine for free.