Wrist exercises?

For those who kept up with my broken bone thread, you'll know why I ask.
For those who haven't...

A couple months ago, or so, I fell and broke my left wrist (I shattered it). I could NOT handle the cast, so I removed it after 2 weeks and 3 days. As a result, my wrist is slightly deformed because one of the bones collapsed (it died).
I can use the hand for almost any task now. I've been twirling my daughters baton to help with mobility etc. But certain tasks are still uncomfortable (like rolling UP the car window).

Does anyone know of any exercises I can do to build up the strength in that hand?