obvious uses are obvious. but i have a better one:
5: to activate an electric barrier. no joke. on the catwalk, every little while, i throw a monkey into like, the tele or something while my mate covers me, then ill run and flick on the trap while reloading. by and large, my team can take out the existing zombies that were crowding around the bomb ( grenades work wonders combined with monkeys..) and i only have to deal with 1/2 zombies on my way back. its really worth it in later rounds when ammo is a nessesity. plus, if i threw it more to the right, everyone who had an STG could grab ammo while i flicked the power.