I'm working on implementing two positional guns into the NRFT right now. There have been a handful of folks that have done it. Mamemaster has a pretty sweet one setup IIRC.
Other games off hand that did: T2, beast buster, space gun, silent scope, deadstorm pirates (not emu'd) any game that natively had a cursor on screen was usually a posgun game.
You can play all light gun games in MAME using the positional guns.