Weights are great. Also pushups pushups and more pushups.
Normal pushups (either off knees or toes) i.e. hands at shoulder level, elbows coming out, lower yourself down to floor keeping back straight (so get those abs working too) and then back up. This works all the chest area, biceps and shoulders.
Tricep pushups - these are killers and great for the tuckshop arms. Keep your elbows right in next to your body, when in the lowered position your hands should be under your chest, not shoulders. You'll probably want to start on your knees for this
and if that's too hard still (and trust me, everyone at booty struggles with these), you can bring your knees forward a bit so you're kind of kneeling.
You can also do tricep dips off a chair or the couch etc. Hands on edge of seat, drop your bum over the edge and lower yourself down with your arms, keeping elbows in close to your body, then lift back up. Try to use your legs as little as you can (but if you need to you can use them to help your arms, like you're doing a squat)
Anything like this tends to work better if you do them slowly too, that way you're working lots of little muscles for longer and you're more controlled so less chance of injury.
Swimming would also be good. And of course losing any extra fat will also help via any cardio you do (thanks Tegan for stating the obvious).
35kg lost. (November 2005 - October 2006)
15kg gained again (as at October 2010).
Back to the drawing board - Let's do this thing!
"You can't change the winds, but you can change the sails"
"Reach out and take control of what lands in your lap"