I have heard of some interesting training tactics in my day to teach pets various lessons. Similar to the suggestion to toss a pebble-filled water bottle in the general direction of a barking dog to get him to stop yapping, this is a noisy device to deter your cat from jumping on the couch.
The Jumpo Trainer ($5) kind of reminds me of a bear trap (only it's not lethal, thank goodness) but designed to make noise to keep your cat or birds from going into places they shouldn't. Once the target area is triggered, the Jumpo jumps up, rattles, and your kitty is scared away from whatever you are trying to keep her from. I'm all for training aides to help me along the learning curve, but I'm just a little skeptical that this scare tactic would actually work . . . without causing a cat to go mental!