MCV has word on the results of Turbine's decision to drop subscription fees for The Lord of the Rings Online, saying the move has doubled the game's revenue. Word: "In addition, a million new accounts have been created and 20 per cent of the game’s former players have returned. Peak concurrency has jumped by 300 per cent and the total active players count has increased four-fold."
So their userbase has increased by 400% but their revenue has only increased by 200%. I'm not really sure that's a great achievement. Still, it's better than most MMOs achieve.