You get one weapon....

[The Warden]

I choose Gordon's Crowbar.

 

[Mushroomfreak111]

CAW revolver grenadelanucher and bucketloads of ammo, or a Bradly APC and the required crew/instructions^^ (it's a weapon, right?

Or a nuclear bomb, so I could die spectacularly and take as many of the bastards with me as I could!

 

[Z of the Na'vi]

A foam sword.

If I'm going to die, I might as well die laughing my ass off at the faces of the "hordes of hell."

 

[Loop Stricken]

Take the black hole summoning power from The Darkness and convert that into a gun.

You get one of those in Mass Effect 2. Tasty Blackstorm.

 

[Jin Hikari]

Either the Lancelot or the Gurren, both in their final forms, from Code Geass. The sheer epicness and the fact I wouldn't ever need to re-charge as well as have unlimited ammo of the uber-weapons at my disposal. Plus, it's a huge robot. How can you go wrong?

 

[RJ Dalton]

My weapon of choice always has been and always will be the Giant Wet Spaghetti Noodle.

 

[Death on Trapezoids]

My original choice was ninja'd by the OP, so...
The MIRV fatman
ratchet's rift inducer
the samaritan
the mysterious stranger's revolver
the morph gun from Jak 3 with powers of light and dark
the Ban hammer
an APU from the matrix
the LAZER!
Actually, the APU takes over all but the ninja'd BFG 9000 for pure badass factor

EDIT: a terran battle cruiser from starcraft with yamoto cannon.

 

[tmujir955]

Cloud's Buster Sword.

Why?

If I'm going to die, I'm going out with a bang.

 

[Dr. Paine]

Spoiler

Vegnagun. Massive, potentially world destroying cannon. All I need is to learn the piano.

If I can't have that, I'll take whatever the biggest grenade launcher is.

 

[icyfresh]

fucking nuke on a stick...
basicaly bfn
BIG FREAKING NUKE

 

[Outamyhead]

Upside down canon from Armed and Dangerous, got to have a laugh while your potentially going to die.

 

[bassdrum]

provided that there's still a good supply of saw blades and exploding barrels, i'd grab a gravity gun.
otherwise, i'd go with a predator drone, so that i could annihilate the denizens of hell from perfect safety thousands of miles away.

 

[Generator]

I'd much like the Needle Laser from Jak 3.

It's an awesome gun that swarms tiny little heat seekers all around you to home in on enemies, and the only problem with it was how quickly it ran out of ammo. Unlimited ammo would make me untouchable!

 

[Infinatex]

Upgraded Colt from COD Zombies C3000 B1at-ch35
or
a good old fashioned Gunblade

 

[Americow]

The M.E.R.V from Fallout 3.

 

[Trivun]

A sniper rifle. Because that's all I ever need

 

[TheSentinel]

Spoiler: Bring It

 

[CloggedDonkey]

I would want a pimped out MP40, Wolfinstien(not sure if I spelled that right) or Cod:WaW style. think about it, awesome weapon look wise, good firepower, and it's compact.

 

[Connosaurus Rex]

the RYHNO(SP) from Ratchet and Clank, heck any weapon from Ratchet and Clank.