I was thinking how much fun would it be to play a Ghostbusters MMORPG. What do you guys think?

Hell yeah!

Better still, it should be a Facebook game in the vein of Mafia Wars, except it'd be cooperative–instead of putting out and taking “hits” against your opponents, you'd be helping them catch nightmarish ghosts instead.

I can see this having the equipment from the Video Game (Proton Stream, Slime Blower/Ghost Gummer, Shock Blast/Fright Freezer, and Meson Collider/Overload Pulse), with options to buy RGB and EGB versions of all equipment.

You might have to buy the RGB “gadget” toys as well, for more “specialized” requirements–in order to get a ghost “up close and personal” for study, you'd need the Grab-a-Meter; if you couldn't “see” a ghost you could use the Ghost Radar Headphones to listen in.

When you start the game your proton pack is fully charged. Whenever it is fired it looses some of its charge. The longer it's fired and/or the longer the stream, the more power it looses. Because of this you have to use your equipment sparingly and must charge it up whenever you get an opportunity to do so. Charging points can be found dotted around in various areas. It is the same for the traps, they lose power and must be charged as well. You can also charge your trap and various points. There are proton charge points, trap charge points and points where you can charge your trap and proton pack up together. If need be you can also link your trap and proton pack so that one can generate some power from the other. It's all about managing your energy, kind of like ‘ammo’ in a first person shooter.

I'd go for it, wouldn't make it facebook-'exclusive' though but that's just me.

And I wouldn't have any of this subscription crap, or “you can use your credit card to give yourself a boost.” You would have to EARN your money by busting ghosts.