Some time back, I posted on the blog about the Williamson Jet Popper (see post) which came in 7inch & 5inch models.
Recently, I found these to be extremely effective for night/low-light popping. The chugging action, splashes and loud "pop"s attracted the GT attention quite well.
Youtube video courtesy of RapalaVMC
Good thing the last GM (Green Mackerel) in the tacklebox converted a strike after busting of a NS (Natural Silver) earlier