The topic on FPS prompted me to write something about Allegiance, one of the few (if not the only one) multiplayer flight sim not being a MMORPG. The game was shipped a few years ago, as a game played exclusively on Microsoft's Zone, and with a monthly fee. But the source code has been released , and the game is now free to play on private servers.
So, a typical game involves two teams, each led by a commander. The commander handles the strategy of the team, while the other players are all flying a ship or another. You may be flying a scout for recon, or manning the turret of that bomber, or repairing allied vessels, and so on. You may switch to another ship/ship configuration once you reach a base, where you will be virtually safe (well, until the base is destroyed by enemy bombers that is).
I do not know so much about the specifics of the commander's work, but I believe she handles the deployment of miners (for more resources), the research of the team, the construction of other bases, and so on. The commander may also give specific orders to your ship, such as "Well, Poor Pilot, please take down that capital ship with your fighter, will you?".
Death is handled a bit better than in most other games I can think of. Once your vessel is destroyed, you will be ejected in an escape pod, with your experience intact. But since a pod isn't exactly the best ship available, you will have to go back to your base to get back into an actual ship (or wait for a teammate to pick you up). If the enemy team wishes to do so, they can also destroy your pod, sending you back to your base. They will get some money, and you will lose your experience, but it will allow you to get back into the fray faster.
Lastly, there are more than one faction available, and "mods" are being made for the game. I would be hard put to give in-depth information on these two areas however; I am just beginning Allegiance myself.
So, out of idle curiosity, are there other players of Allegiance here? If you would like to check it out, the main site is available
here, along with the game download (slightly less than 60 mo; low speed Users, beware!).