http://waronline.net/
Just found this game today, it has a very good tactical engine, a kind of totalwar meets chess. It's free, you play it online vs other people. Turn based, hex based with a very strong rock-paper-scissors and a wide unit choice. Currently it is medieval period vs demons. You can play battles or campaigns, and there is a ranking/ladder system for both. Developed by one guy from australia who plays it all the time and make improvements.
~:wave:
