hi kristen,
hope the ankle isn't too sore!
from my own experience with ankle surgery (plus i'm a PT) here are a couple of things you could try:
1) obviously you will be pretty limited in terms of what you can do at the moment physically, but the fitter and stronger you keep yourself, the quicker you will bounce back. i was non-weight bearing for 8wks, but i managed to rig up an arrangement with an exercycle so i could still do some cardio work - basically with my sore foot resting on a stool, and my other leg pedalling. anything you can do to get your heart rate up, and keep it up for 20min or so will be great for you - as long as you protect your ankle.
2) although you can't work on strength/range of motion in your ankle itself, you can try to keep some activity in the small muscles in your foot. try and imagine lifting up your arch inside the cast/boot. as long as it doesn't hurt your ankle this is something you should do throughout the day.
3) you are probably spending a lot of time with your leg up (and if not, you should be! don't let it get too swollen!) - but make sure you are not getting short in any muscle groups. spend some time lying on your tummy and stretch through your hips and quads. also your hamstrings.
4) you could also look at some core stability work to get a strong base for the rest of your rehab - there are plenty of things you can do in a lying down position.
hope that helps!
cady