I just had a foot cramp a few minutes ago. I never quite figured out how to deal with these little buggers. This time, I decided to immediately search the web for some tips, and I was very pleasantly surprised with this video that explains very clearly how to deal with foot cramp. I followed the instructions, and to my amazed relief, they did work!
Here is the link to the video for your and my future reference:
How to Deal with Foot Cramp