I'm talking not about how HARD IT KILLS UGUGHGUHGUH.
Rather more about the presentation y'know?
The art, the sound it makes, yeah? I mean other than the novelty value, the farsight from perfect dark was pretty damn lame, and the M1 is getting a bit tired eh?
So what's your fave game gun, going by design rather than actual usability. Or real life accuracy for that matter,

The land-shark gun in armed and dangerous was pretty kickass...

Gravity Gun from the Half Life series.

i can only agree.

stakegun from painkiller
oh yes and this other one that shoots shuriken and lightning ;]

I know it's not really original or anything, but sniper rifles and shotguns. I particulary liked railgun from Red Faction, that was used as sniper rifle with very low rate of fire, and could shoot trough walls. And when you were looking trough scope, you saw heat signatures from other players ... That were, for example, behind the wall... Seriously, that weapon was awesome as long as you were holding it :D

Guys ... Gun Number 6 in Painkiller shoots SHURIKENS AND LIGHTNING. I swear it could only be more awesome if it had tits and was on fire! (ahem).

If mods count, then my winner is charged capacitor from UT2k4 JunkWars mod.
And without mods it would be....hmm...either german field spade from Day of Defeat, the Stakegun from Painkiller or SKS Simonov from Vietcong (that weapon is nothing special, but I like it anyways).

I'll have to go with the Flak Cannon from the Unreal Tournament series. There's just something about it that screams "Get outta my way, motherfuckers!".
Also, the Impact Hammer from UT3. While you can hear it coming a mile away, it's also a great feeling of power seeing everyone run from your immediate vicinity. It's a weapon that's truly up close and personal.

My favourite from JA2 was the H&K G3a3 (which I kitted out all my mercs with mid-late game).
Good power, range, etc.. Plenty of ammo available, and made a nice gunshot sound! :)

From COD4 I quite liked the Heckler and Koch G3 rifle with the ACOG sight on it.
Also the Barret .50 for sniping, though hip firing the mag rapidly and the shot going through a wall and killing someone prompting calls of 'cheat', and 'wallhack' are funny.

I'll murder the next person who says the Gravity Gun. Also, it's in Half-Life 2, not Half-Life series
My vote goes to the BFG from Doom. Not Doom 3, but Doom 1 / 2.

+1. For me, specifically the Quake 2 version. The rays were really clever.
Also, the ASMD shock rifle from the Unreal series. The idea of a weapon combo was really neat.
Finally, the Quantum Singularity from the Chaos mod for UT/Q3/one of those. Watching your opponents being helplessly sucked to their doom is just fun.

I think, I'll go with the Minigun in Serious Sam.
Also, the Rail gun in Quake II is awesome.