Jump rope is great.  Doing 50-100 reps with pushups, ccnurhes, squats, lunges in between sets. Jumprope is great for your core (tummy), chest, arms, butt, etc.  Also, running or walking uphill is great for the legs, butt and calves.  Hiking or stair climbing does wonders for your butt and legs.  Some say it bulks up those areas but I've found the opposite to be true.