It might not be all that pertinent, or it might be...
I reckon the most flexibility with strength (in the wrist area) I've ever seen is possessed by Arnis / Kali stick fighters.
If you could find someone to teach you Kali before too long you will have very strong AND very flexible wrists.
Other martial arts which involve finger / wrist / arm locks, throws and restraints give you very strong and flexible wrists.
I know several wrist stretches but I have a hard enough time getting students to do them properly while I'm demonstrating it (its a bit of a contortion)...hmm I'll try...just for you Pele 
1) up / down wrist stretch.
take one fist, and cup it in the other as if you were going to do that traditional sorta bow that a lot of martial artists do. One fist in the other hand with the outer fingers resting on the top of the fist hand. Then open the fist so the fingers on that hand are pointing straight down. Slide the other hand along the top of the fist hand (although it isnt a fist anymore
) til the heel of the top hand is resting on the top of the lower hand, 1/2 way between the knuckles and the wrist. Bend the fist hand wrist so that you can feel a stretch in the top of that wrist. then apply pressure with the other hand. If It hurts release some tension.
<phew> thats one.
2) side to side stretch...this is too hard Pele..I dont know the medical terms for the movements... 
Ask an Aikido instructor to teach you some wrist stretches...they will know more than I do. 
I did try 
1/2 points ok?
Josh
seeya,
Josh