The RC-P90 from Goldeneye.
The Cerebral Bore from Turok 2.
The Firestorm Cannon from Turok 2.
The Laptop Gun from Perfect Dark.
The Rocket Launcher in Halo.
The Slayer Rocket Launcher in Perfect Dark (control the rocket in first person)
The Flak Cannon in UT
The PKM in Desert Combat
The Assault Rifle in Desert Combat
The Magsec 4 in Perfect Dark
The gun in Perfect Dark that looked like it ate 2X4s as clips (can't remember name)
Farsight XR-1 in Perfect Dark (Look through walls 'til the end of the level!!!)
The BFG 9000 (no explanation needed)
And who can forget the C4 in Battlefield 1942/Desert Combat
Good times
