I did the On Your Toes workout the other week, it's a leg workout where you do all the exercises standing on the balls of your feet. Felt effective. Otherwise it's calf raises, calf raises and some more calf raises.
Find you a step ladder and go up and down it repeatedly until you give out. At least you be going somewhere :-)
Try skipping rope, a great multiple purpose work out. Cardiovascular plus a great way to get those heart shaped calf muscles.