Seated arm workouts???

Hi, I am getting married in 6 months and wearing a sleeveless dress. I'm looking to tone up my upper arms. This wouldn't be a problem if I hadn't been chronically ill since February. I am unable to stand for long (ok, even normal) periods of time. Are there any workouts anyone knows of that I can do from my couch? I know it's not going to burn as much, etc. but Jillian Michels is just not in the realm of possibilities right now!