This year marks two important milestones for George R.R. Martin fans: the 20th anniversary of A Song of Ice and Fire appearing in print and the 25th anniversay of George starting to write the first book.
George started writing A Game of Thrones in the summer of 1991. The novel was published on 6 August 1996. However, that wasn't the first time any Song of Ice and Fire material appeared in print. That honour came three months earlier when his publishers started rolling out various excerpts and outtakes from the novel.
The first thing to appear was a sample booklet from HarperCollins Voyager, George's UK publishers. This booklet contained the first 124 pages from the novel (running up roughly to the end of the chapter where Robert tells Eddard about Daenerys's wedding) and was published separately in the UK for 99p (but now retails online for £150!). It was sold at bookstores across the country as a way of whetting the appetite for the book. My three local bookshops cunningly positioned the booklets next to the hardcover displays for the seventh Wheel of Time novel, which was released on 15 May 1996, to get some cross-series fantasy promotion going on.
In the United States, Bantam ran an excerpt in Asimov's Science Fiction in July 1996 (published in June). This excerpt was huge. Dubbed Blood of the Dragon, it contained all of the Daenerys chapters from A Game of Thrones assembled into one self-contained novella. Blood of the Dragon went on to win the Best Novella prize at the 1997 Hugo Awards, making this the only literary Hugo the series has received so far (Game of Thrones has won three for Best Dramatic Presentation, however). A Storm of Swords got the same treatment in 2000 when the Daenerys chapters were pulled out to form a novella called Path of the Dragon, although this didn't win a Hugo.
So there you go. Although the anniversary of A Game of Thrones itself isn't until August, when we'll see some fancy new editions hit the shelves and likely some more celebration of the fact, A Song of Ice and Fire has now been in print for more than twenty years.