Whatever happened to the energy pack? That'd add a few shinys I'm sure.
As for attempts at new suggestions...
-Explosives-
Proxy Mines: Small bot-controlled explosives. After deployment, they wander around after whatever player gets close. Great for deathmatches!
A few more standard grenade types: Could revamp the Flashbang for T+T, as well as create a Frag Grenade. Perhaps some C-4 remote explosive?
Howlitzer changes: I know the Howlitzer was meant to be a secret, but perhaps making it a deploy weapon/increasing it's splash area would make it much more viable for large outdoors battles?
-Medical-
Medi-Beam: Basicly a Tier-Tac Medigun, not nessisarily with the secondary ubercharge effect but could still be a continuous healing effect on a locked target. A personal suggestion is it could work on a 'overheat' system, meaning instead of constantly following a person healing them you'd be forced to use it sparingly.
Healing Grenades: Toss one of these and it explodes into a healing mist.
Medic SMG/Assault Rifle/Bullpup: If you play Killing Floor, they have medical weapons that have a secondary heal dart attached to them. Revamping the SMG/Assault Rifle/Bullpup with similar would allow some 'combat medic' concepts.
-Misc.-
HMG: Heavy weapons designed for base defense. Require deployment, and brings back the 'overheat' from earlier LMGs, but hose out tons of bullets.
Flak Cannons/Guns: Anti-air weapons, which fire small shells that after a small while explode into fragments. Designed for antiair weapons. Naturally the heavier it's potential or stronger it is, the more it may require deploying.
Multilaunchers: Grenade Launchers and Rocket Launchers that trade damage for firing multiple projectiles at once, either right after the other on the first fire or able to be fired individually.
Tankhunter Sniper: A sniper rifle with explosive bullets. Unsure if Tourqe can do it, but basicly a raycast sniper rifle which spawns a explosion and strong damage at the firing point due to armor-piercing shells. I'm picturing it being a one-shot weapon similar to the Crossbow and requiring a long reload time.
Auto-Crossbow: A lightweight, cartridge-fed crossbow easier to use on the move, able to fire 3-6 bolts or so before reloading the cartridge.
EDIT: Though a few of these ideas are more suited for anti-vehicle (Flak Cannon, Multilauncher, Tankhunter Sniper) The rest of them probably could find their way into the MAS testing servers I've been hosting. Need to work on the next build anyway, come to think of it... Noticed you wanting a test bed, so just offering.