Web browser based games have existed in one form or another for a while, evolving from simple 2D affairs to what we have today. But imagine a future if you will, where you could play any title you could think of without even downloading a client: all you had do to was open Firefox/Explorer/Safari and point yourself to a website; we might not be too far off from this being a reality.
One of the most prominent browser-based games is RuneScape, a long running MMORPG, and Kuma Reality Games has also made a variety of free episodic FPS titles available. Now, however, big name developers are getting into the browser-based scene, with EA launching Battlefield Heroes and Battleforge, and id Software working on Quake Live. We've had executives talk to us before that said "the web browser is the largest platform in the world" and there's a good deal of truth to that. It soon might be that all games are downloaded into one sort of a browser or another, making all the current format wars seem silly in retrospect... only time will tell.
[Pictured: Battlefield Heroes]