I don't often post details of multiplayer games, but I thought I'd make an exception with this one because I'm really impressed with it. I don't think it's as versatile as America's Army, which is another I rate highly, but it's still a good one. Check out the following for some ideas as to what it looks and plays like:
http://uk.youtube.com/watch?v=Jxt0wYErahY
Rising Eagle: Futuristic Infantry Warfare v1.3.1 Free Full Game
Developed by Invasion Interactive Ltd., Rising Eagle: Futuristic Infantry Warfare is a multiplayer, team based, tactical first person shooter set in the near future, circa 2040AD, in a world where the USA faces new contenders for superpower status. Players participate in the conflicts of tomorrow in urban and open field infantry combat. Rising Eagle: Futuristic Infantry Warfare is now available for free - the install includes all maps, full gameplay features, unrestricted online play, as well as listen server capabilities (host from within the game). This release includes many bug fixes, including key mapping - visit the official website of the game for details: