Since Activision purchased the Guitar Hero franchise in early 2006 along with original publisher Red Octane at a price of nearly $100 million, the series has surpassed $1 billion in sales.

At a recent presentation for industry analysts, the publisher announced that it certainly wasn't done with the popular series. Activision Publishing president Mike Griffith confirmed that they would be doubling 2008's Guitar Hero output for next year, and that by 2010 the output would be set to triple.

"We've learned that the consumer still has an insatiable appetite for more," Griffith said according to gamespot.com.

It's an assertion that the sales figures certainly back up. Guitar Hero: Aerosmith, for example, generated more revenue than any of the band's actual albums, while a song like Weezer's 'My name is Jonas' has seen a sales increases of more than 1000 percent since its Guitar Hero debut.

The upcoming Guitar Hero World Tour is set to expand the Guitar Hero format into a four-piece set-up that would include drums and vocals, but Griffith alluded to even more innovations around the corner.

"Beyond this, we have a step-change innovation plan already in development that takes our game experience in new and exciting directions...which we'll announce at a later date," Griffith said.