SAGA is a game that's had an interesting subscription model from the getgo, shirking the typical subscription fee model for a CCG-esque booster system. Once you've bought the client, the game is free to play. The only caveat is that you can only get additional troops for your army by purchasing "boosters" for an additional fee. It's really a pretty brilliant system, combining two types of games (CCGs and MMOs) that are independently addictive, and fusing them together into what one would have assumed was a license to print money.
We haven't really heard how the game has been doing since it's since it finally emerged from beta last week, but already Wahoo Studios is shaking things up in an effort to draw in players. Like a drug dealer looking to give clients a first taste to get them hooked, they're now offering a free version of the client to give would-be players a better idea of what's on offer. The free client is missing a few features, but a free something is always better than nothing. Unlike a trial though, there is no time limit on how long you can use the free client. Seems they're confident in their product. It's probably worth a shot if an MMORTS/CCG sounds up your alley!