The game has:
The Black Hole Cannon (excatly what it says it is, later ripped off by Up Your Arsenal)
The Shark Gun (Actualy makes sharks that come up from the ground and eat your enemies)
Topsy Turvy Bomb (Litterally turns the world upside down and makes nearby enemies fall upwards to their doom.)
Those are the three that stick out. I never bought it or finished it.