Have you thought about trying Yoga or Pilates? I just picked up a DVD at the library called "Pilates Complete for Inflexible People", LOL. The name of it just made me chuckle because I am definitely in that category. I'm not sure how good the instructor is -- but I'm willing to give it a try.
Also, water aerobics & swimming shouldn't be too hard on your ankle.
Good luck to you, and hope you'll be posting with us lots!