Apple has allowed a video-game company to offer its titles by subscription on the iPad.
Big Fish Games, has become the first to offer users access to dozens of titles for $6.99 a month. They make some of the most popular games available. You are probably already playing at least one of them.
UPDATE: 10/24/11 Apple has just removed this from the Apple App Store. Big Fish Games has no idea why, and Apple declines to comment.