Hello,
in my defense, I have searched the threads here, the feature requests list at sf.net, and the scrapped ideas list and I've found nothing, so here goes:
My favorite squad based tactical game is definitely Jagged Alliance 2. The thing that sets it apart the most, in my own view, is the fact that the characters have personalities that are somehow intertwined in their own mini soap opera - some will love others, and some will hate the first and refuse to work them at all. I strongly believe that this feature is the main thing that kept my usually very short attention span on finishing that game time and time again.
Now, I understand that the x-com series traditionally comes with random noname characters whose only differences are their ability points and this is technically how a normal professional military organization would work, but for the long campaign game's sake I think a small random interaction system could be utilized. It doesn't have to go as far as hate and love, but it would be interesting and realistic enough to see some rivalry between the two best shots in the squad, for example, or a feeling of appreciation if another soldier has saved you from a nasty alien attacker. There could be a racist soldier who wouldn't work with Asians, or whatever. In the most radical (1% chance) case scenario a soldier would prefer to go back to his original army unit instead of working with someone else.
I'm not a programmer - and as I read through the Tactical Deployment thread's latest responses, I was almost discouraged to post this here - but I'm pretty sure that this can be achieved with a mini xml database of sorts with the squad members and their general feelings for each other, entered at random at startup. Depending on that, they will (mostly) say and (less so) do stuff to each other throughout the tactical phase of the game, thus improving the overall game experience. What I can actually help with about this is writing the lines for the characters. Waiting for your input.