Well, now that there's a more recent topic for ideas for uniques, I don't have to resurrect the age-old one.
MP40-From: Well, there's a lot of games that have MP40s, and it was an actual World War II-era gun last I checked...
-Stats:
Damage: 1d8x4
Accuracy: +5
Base Fire Time: 1.0 second
Base Reload Time: 1.2 second
Clip Size: 32
Ammunition: 10mm ammo
Special Reload: N/A
Quote on pickup: N/A
Ingame Description: An antique infantry weapon.
-Intent: This was designed to be just a more potent chaingun. Fires one less bullet per volley and has a smaller clip, but is more accurate, more damaging, and most of all, MUCH faster to reload. (You'd be surprised how important that is.)
Firebomb-From: Rise of the Triad
-Stats:
Damage: 8d6
Accuracy: +4
Base Fire Time: 1.0 second
Base Reload Time: 1.5 second
Clip Size: 1
Ammunition: Rockets
Special Reload: N/A
Quote on pickup: We'll bury them in a lunchbox!
Ingame Description: Nothing short of fiery death. Make sure it doesn't backfire.
Notes: The explosion for this weapon is quite different. Instead of a round blast radius, it explodes in an 'X' shape, with one of the 'arms' being focused on the direction the weapon was fired from. The 'X' is 6 squares in each direction from the point of impact, and anything within 1 square of the actual blast takes partial damage.
-Intent: Different style of rocket launcher - more damaging (I believe the Firebomb was about twice as damaging as the Bazooka, the equivalent weapon to Doom's Rocket Launcher, in Rise of the Triad, but I had to tone it down in this case) but exploding in a much different and potentially much more dangerous pattern.
Note that I DEFINITELY need better ingame descriptions for these. I also need to work on the quote on pickup for the Firebomb - the one there now is the first one that came to mind, one alternate was 'Ludicrous gibs!', but neither one feels right. (But both are quotes - the 'lunchbox' one slightly altered - from Rise of the Triad, the game where this particular Firebomb came from.)