Do you remember from the mid-90's there was a home gym called the Healthrider? Well, we've had one since 1997 and we have moved twice and refuse to part with it. It uses your own body weight as resisitance and you pull on the handles and simultaneously push on the foot pedals. By changing you hand position, you can work biceps/triceps, and all upper body muscles. If you put the handle in the position closer to your seat, it becomes a pure lower body/ab workout. There's three height positions for increased intensity (I've never put it above the lowest setting and still get a pretty good workout). It is a great toning machine and you can get them cheap on craigslist or Ebay. If I haven't used it in a while, I'll get on it, go for 20 mins (changing hand and handle positions every 4 minutes....5 sets) and the next morning I'm pretty friggin' sore.
I'd consider one of these if you can find one. The don't take up a ton of space. Good Luck.
