+1, Spun Sugar. I use a device called the Walkydog. They love it, and I get a bit of exercise. However, after they get used to the exercise regime, they'd probably still jump that tiny fence to greet people. One suggestion I haven't seen yet is sticky tape or contact paper on the top of the fence so when they put their feet up there, they get stuck to the paper, which they hate. I've heard this works for "counter surfers" (dogs that get up on kitchen counters), so it might work for you since the fence has a flat top. Like the mousetraps, it's good because the fence seems to do the negative reinforcement, and you get to be the good guy and "save" them from the nasty sticky stuff. You'd have to replace it a lot, however, especially in bad weather. Good luck!