Personally, I think it would be a great pintle-mounted machine gun on a vehicle, maybe with the magazine moved to the side. There's many sci-fi model vehicles that would look great with IMEF figs and the rifle would be a great way of bringing the vehicle and figs into the same universe.
That's a GREAT idea! I've been focused on trying to put together a drop-ship to work with the IMEF, but it would also be nice to have some sort of futuristic APC or Hummer-equivalent to ferry them into adventures. By having a pintle-mounted weapon that's visually similar to their rifles in style, that would help to provide a visual link to tie vehicle and figures together. I suppose I just need to find a suitable vehicle.
I've been keeping an eye on the Avengers "Stark Tech" vehicles in the local toy stores, hoping for some sort of sale, as a possibility.
For instance, there's the Stark Tech Goliath, which I think could be converted into an APC fairly easily, since even though it's intended for 3.5" tall action figures, there's no easily-identifiable cockpit. I'd just need to use some plasticard, etc., to build a rear compartment and boarding hatch, but some discs over the wheels (so they're not so obviously hollow), repaint everything, and consider some weapon swaps.
For aerial transportation, I was thinking of getting the Avengers Quinjet. It, again, is meant for 3.5" action figures, but, being a toy, it's grossly out of scale for those figures anyway.
It actually has a drop hatch in the back that, in the movie, would have been a boarding ramp for troops in the back, though this toy just has a seat for a SINGLE character back there. I'm aiming for a model, not a play-set, so I could perhaps take the toy and gut the seating interiors, either going the cheap route and making it so you *just can't see* what's inside, or else going the extra mile and installing some seats within the cockpit area (showing that it can seat more than just one person at 32mm scale), and putting some benches and equipment racks in the rear hatch area.
Of course, at this point, I'm not really talking about Bones conversions, as I am talking about conversions to unrelated toys that I'm thinking of making to use WITH my Bones models. ;) Sorry!