Diamond Sutra, the world's earliest dated book (which also happens to be blockprinted). You can also look at the scroll on their site.
What I also interesting about this was the colophon attached to the scroll, which is the oldest copyright notice I've ever seen: "Reverently [caused to be] made for universal free distribution by Wang Jie on behalf of his two parents on the 13th of the 4th moon of the 9th year of Xiantong [i.e. 11th May, AD 868]".
I do have to say I'm fairly impressed with the Bristish Library's Website, even if it is difficult to navigate at times.
You can also take a look at the Gutenberg Bible and Leonardo DaVinci's notebook.
Although the Chinese invented printing and movable type printing had long been in use in East Asia, the Koreans actually took printing to another level by developing movable metal type printing years before Gutenberg's invention of the printing press.