There are some things we can rule out with when musing over what George R.R. Martin might develop for HBO now that he has a two year contract with them. Certainly not something comedic, he's not that type of guy. A Game of Thrones prequel of sorts though? Maybe, according to this interview with IGN.

It's not the only idea that's been talked about, of course, but it's one of them. What do you think? Would you be interested in a prequel based on his Game of Thrones novellas?

Game of Thrones - George R.R. Martin Talks GOT Prequel Series [IGN]