One thing I would dearly love would be a battlebot. Not a HWP, but some sort of contraption that looks like it realy did come from battle bots.
I want this contraption to fight Crysilids with!

It would have to be a weakling, a sort of wimpy little guy that might, MIGHT slow down the Crysi enough to get off an extra shot or two.
Maybe something like a Pit droid from Star Wars?
Also, with such things like Hondas Asimo being developed now, it would not be out of the realm of imagination to have such a weapon available when the aliens arive. And maybe they could be upgraded with alien tech.
But, I would suggest keeping biped battlebots weak so they dont take away from the human grunts.
Maybe limited to a small built in weapon, IE eary on a assault rifle, later on a laser pistol. Also, limited in hand to hand. I imagine an Asimo haning onto the leg of a Crysilid as it stalked toward the nearest grunt.
Maybe slows the Crysilid down, but does no damage, and is easily swated into robot heaven by the alien.
Just a thought.
A small, humanoid, roboit "light" trooper.
Also, the rookies will appreciate not being used as plasma fodder!
Just send in a Pit bot to scout, but dont expect him to be rambo.
They could be funny also, say if they take combat damage they might hop around on one leg with 1/3 of their base movement.
Since they would not be completely refined, they cold disobey or screw up orders. Or maybe there are certain alien "hackers" that could implant a virus in their software turning them into sleeper terrorits.
So, after you just raided that alien research ship, you are sent to a terror attack. Your squad of little robots leave the transport, the hostile programing is triggered, then they start trying to kill civilians!!!
:o