Don't know if it's been mentioned (and hate to dig up skeletons), but the only f2p [former] SE product I know is/was Fantasy Earth. http://en.wikipedia.org/wiki/Fantasy_Earth:_Zero
But I agree with most people. SE has never given in to the whole "Pay this for free! You'll get bored of it in 3 months anyways. There's a new game on the horizon! Buy some fake currency!" model that many kmmo's have established. If they ever do, ffxi will go first (they literally said that they didn't expect the game to last this long. But it's still making money so they keep it running/adding stuff.). If this game is/was, that big of a failure, they certainly won't go the f2p model. That's one thing I like about companies like square enix. They have a passion for what they're doing. They'd rather have a great product that failed than an army of shallow product that they can wh*re out.