There's a preview chapter for Daenerys at the end of A Feast for Crows, but there was a different preview chapter on Martin's site some time ago, featuring Tyrion. Now it seems there's another one, this time in the North with Jon Snow: http://www.georgerrmartin.com/if-sample.html
The update page has been updated(!) also: http://www.georgerrmartin.com/if-update.html
I have grown old, it seems, waiting for the next installments to come out, and I wasn't in at the start. :( IIRR I read the first two volumes not long before A Storm of Swords was published.
I got completely addicted to the ASOIAF message board for a couple of years, and had to tear myself away so that I could have a bit of outside life.
And GRRM, whom I've actually met and talked to (he's wonderfully accessible to his fans, and altogether delightful) at the World SF convention in Glasgow a couple of years ago, is a number of years older than me. And not exactly superfit! :( We all need to pray to whatever gods we believe in for him to keep in good health and not die until he's finished the series. Whenever will that be? There's meant to be at least one more volume after A Dance with Dragons, and most of us on the message board thought he'd need more than that.