A small shuttle capable of recovering up to 3 injured marines from anywhere in in battlefield. Must be manned by a doctor, and "summoned" by squad medic with appropriate beacon.
Benefits:
Ability to recover severely injured marines from anywhere in the battlefield without need to drag every marine with broken chest or head to the shuttle, and then go all the way back. Since most of the injuries are from FF, this will reduce the amount of time they need to wait to evac by at least 10-20 minutes, personnel needed to drag the injured to the drop ship and they are assured that they still fight without worrying about the injured on the ground.
Details:
Once a medic gets overwhelmed by injured marines in the battlefield (Specifically broken bones in chest, skull, missing limbs), he can stabilize them and activate the medical evac beacon. There are 6 evac beacons in each medical vendor for them which can also be ordered from RO.
A doctor (on sulaco) will enter the med shuttle and turn on the autopilot. The shuttle is equipped with 3 roller beds, one IV, special medical vendor on the wall, and an machine that will lift the injured marines up from the battlefield (Basically, a very small, tight shuttle with one doctor).
The medical shuttle will proceed to the location where the beacon is set and hover above the beacon (more info in section below). Once in position, the machine will automatically drop down the line where a bed is attached to it, where a squad medic must secure the injured guy to the bed on the surface. Doctor then activates the switch and the guy gets teleported up.
(Think of it like this, but a bed instead of that man on the line, and a squad medic securing the injured marine to it. And of course, land instead of sea, and shuttle instead of the helicopter... .-.)

Implementation:
It is quite easy actually. The only thing that requires (little) actual coding is the machine/bed.
Make a new shuttle in the hangar with it's own shuttle areas. One shuttle area in the hangar, second in the Centcomm transition space, and the third one also in the Centcomm space, but with blue tiles representing that you are above the surface of a planet.
A medical beacon is nothing more than a location where the machine will spawn/drop the bed.
Once the marine is secured to the bed, a doctor activates the switch from the inside and it pulls the marine up. He unsecures him and moves him to the roller bed. He sends the bed down again.
For balancing, if there are 4 humans (includes the doctor) on the shuttle, code will prevent any more from climbing up with that bed. Tier 1 aliens can climb up to the shuttle by clicking on the line/bed (also no more than 4 aliens on top), and the shuttle is auto recalled after 2(?) minutes after it stars hovering above the surface (Has to refuel?).
Beacon cannot be activated in the caves or on the space station.
For simplicity reasons, the line/bed/machine is unacidable, c4 proof and explosion proof.
Once it docks back, it starts refueling and takes about the same time as drop shuttle for each trip.
Simple, balanced, useful.