Saw that Medusa in Popular Mechanics once. I'd love one ^_^
.600 NE break-top revolver - the "Earth Shaker" - used in Bubblegum Crisis 2032 as an anti-cyborg sidearm by officer Leon McNichol.
Hezi SM-1 - bullpup M1 carbinoid. Preferably tan, maybe black
Bushmaster M17s - bullpup Bushmaster ARoid. Almost very Seburo, with proper trim, this *would* be a Seburo.
LeMat in .357 and 20ga (or 12ga if I'm feeling peculiarly masochistic -- wait, the FRAG-12 grenades won't be made in 20ga. Definitely 12.)
Bushmaster Armpistol with myoelectric solenoid trigger, embedded in blue enameled gauntlets - for those times when playing Mega Man X just isn't enough. Bonus points for muzzle-whistles and tracers.
Carbon-15 pistol with 100 or 200-round drum, registered auto sear, and lots of tracers.
Whatever big-bore pocket auto Armitage carried in "Armitage the 3rd".
Pancor Jackhammer with modified Barrett muzzle brake and lots and lots of FRAG-12 grenades.
Barrett M82a2 bullpup heavy (.50bmg) rifle
Maadi-Griffin MG6 .50 semiauto, with custom drum-and-belt magazine, cut down into the Mardi-Gras .50 Entry Weapon. With lots of Raufoss exploding tracers and a high-powered green laser sight for that Halo feeling.
The Magnum from Halo 1, complete with teleoptic scope and exploding hollowpoints with a tungsten rod driven down the center. (Beastly!)
Covenant plasma pistol
PPG (Babylon 5)
BH-209i and AP-130b (Schlock Mercenary... no direct links, you'll enjoy finding 'em for yourself!)
Hm.
Hard to top the AP-130 with a neural linkage targeting system.