His #1 choice that was published this year? Tom Reiss's The Black Count. This book is the true story of the real Count of Monte Cristo, Alex Dumas. Alex Dumas is relatively unknown today. However, his story sounds extremely familiar, as his son's (Alexandre Dumas) novels The Count of Monte Cristo and The Three Musketeers were greatly inspired by his father's life.
Martin noted, "I never knew anything about Dumas' father before reading this book. His astonishing adventure-filled life became the inspiration for many of his son Alexander's novels, including a prison stay that inspired The Count of Monte Cristo.”
Martin's other favorite books this year (that weren't published in 2012) were Stephen King's 11/22/63 and Susan Orlean's Rin Tin Tin: The Life and the Legend.
This list will give fans something to read before book 6 of the Songs of Ice and Fire series comes out (it'll probably be quite awhile, knowing Martin's slow pace and long-winded writing...it took him SIX years to write A Dance with Dragons, the fifth installment) and before Season 3 of the HBO adaptation resumes on March 31, 2013 (the episodes have been lengthened! Yipee!)
If you need to further your George RR Martin fix, you can also see him read from a portion of the sixth book The Winds of Winter.
Correction: This post formerly stated that A Dance with Dragons was Book 6 of the Songs of Ice and Fire Series. It is Book 5.