I've mustered a few ideas for the new UGX mod, thought I'd drop 'em on you.
1. Royal Flush Perk-a-cola
-Has a nice, Art Deco design, poker themed.
-Increases power up drops slightly, but more prominently double points.
2. Mossberg M590
-Pump action combat shotgun
-Very versatile and attractive, could be used as a replacement for the Olympia as a starting weapon. (M590 and the G3)
3. Custom grenades (Replace fragment grenades if possible)
-Incorporates new elemental system
-Wind grenade, works like a weakened thundergun, but pushes in all directions
-Freeze grenade, slows zombies, freezes a zombie if it hits the thrown grenades
-Incendiary grenade, yes there is a molotov, but this functions the same, but with a bit more power and incinerates a zombie if it hits the thrown projectile
-Electric grenade, momentarily paralyzes zombies, plays electrocution anim. on affected zombies
Post your feedback in the replies, how any of these are obtained is up for debate. Go wild!