I simply can't stress enough a) a riser of some sort (plenty to choose from...I have a Griffin iCurve and like it very much) and b) an external keyboard.
You'll get the best of both worlds: desktop style ergonomics and comfort AND the ability to unplug the keyboard and take the PowerBook with you when you go. I love this set-up more than anything I've ever owned.
You'll thank me if you spend ANY amount of time typing!
Trust me...I damn near kinked my back, shoulders and neck to death (hunched up, leaning forward, looking down, etc.) before I
wised up and got a clue.
