So yesterday I tried this sourcemod called Empires. It's pretty impressive. One person from each team gets to be the "commander" and have an RTS overhead view of the map, from where they can build buildings, create vehicles and order around the players. Everyone else gets to fight, driving tanks, jeeps, APCs or going on foot. Anyway I'd recommend it if you want something to do. The download is 754.6MB and is available from GameArena at
http://www.gamearena.com.au/downloads/details.php/empires-mod-client-v21-for-halflife-2

Enjoy~~