Being that I plan to be a computer geek forever and ever, I don't want to be held back by carpal tunnel or something awful like that.  Here's what I've learned about Ergonomic solutions for computer geeks world-wide.  (This is just general ergonomic information...  Reviews of actual hardware is elsewhere.)  I take no responsibility for any repetitive motion injuries. This information is derived for other web sites I've read.  It's validity is reliant on theirs.

What is Ergonomics:
I think everybody knows 'what' it means.  It's simply positioning yourself and working in a way that reduces strain and risk of injury.  Easy enough.

Posture:
Most guides I've read say that the best posture is as follows:

• Feet flat on the floor.
• Back strait, not hunched.
• Forearms level with keyboard.
• Wrists not bent.  (Keep em' strait.)

These are the suggestions for good, ergonomic posture, but you have to find what works best for you.  It usually takes a lot of tinkering to find a few positions that you are comfortable with.

The Interface:
The keyboard and mouse are your tools of input.  They can also be your enemy.  All those repetitive motions are very hard on your tendons, wrists, etc...  After years of use, the damage begins to add up.  (From what I've read, mice are the worst.)  Once you've got real damage, it usually doesn't go away easily (if ever.)  It's worth it to invest in good equipment and use it effectively to reduce strain.  I've written up some reviews of a few ergonomic interfaces.  They're in the tech section, if you want to have a look.

Good luck...