Sometimes leg cramps can be caused by vascular issues, sometimes they're neurological in nature, causing the muscles to cramp up.
They make over the counter meds such as Q-vel (I think that's what it is) -- it's quinine. (Or you could just drink tonic water!) But quinine (PROVIDED YOU ARE NOT PREGNANT!!) has been used for ages for leg cramps.
Also, adequate intake of magnesium -- it is a muscle relaxant. In fact, magnesium is given to birds in captivity when giving difficult births to ease contractions. One of the best forms I found was a powdered calcium/magnesium combo that you just added to hot tea! It was amazing, and it also was very soothing and calming. It worked great.
I used to get horrible charlie horses- the first time it happened I didn't know what it was and was terrified let alone in horrible pain. Since I quit dance I rarely get them, I took celebrex but I found only rubbing it gets immidiate relief, maybe even a heating pad. Last night my toe went in a horrible cramp in the shower...but it was more amusing than anything else.
"Careful the things you say, children will listen.
Careful the things you do, children will see.
~Into the Woods