CarrionCrow: -laughs- More like early-onset arthritis here. Your idea would be more fun, getting what I describe as claw hand after playing games for a while gets old.
I spent some time in a medical facility with a lot of elderly. I remember one woman (must have been 75-85 but in bad shape) whose forearm muscles were hypertonic to the extent that she had no extension at all.
The therapist would come in every day and try to slid a thin cone between the thumb / fingers to try and create any gap at all. It's made me a bit paranoid. I've though of trying to design a therapeutic glove that could help, but then I don't hold any degrees in medical engineering.
But the basic idea would be some sort of tension to push/pull the fingers gently towards full extension while relaxing the muscles and connective tissue through the wrist and forearm. Maybe such a thing exists but I've never seen one.
Barring that, I mostly just try and make sure to spend 3-5 minutes every day doing some finger/hand exercises after all the time I spend with them curled at work, and playing games or music.