In regards to making computer usability easier, there is WorkRave. This program runs different timers to alert you to take incremental rest breaks(it calls these micro-pauses), full rest breaks, and helps restrict you to a daily usage limit. It also recommends little "at desk" excerises you can do to release tension/stress. Been running it for a day now, very helpful. Runs on Linux or Windows.

http://www.workrave.org/