The library has been archiving congressional and presidential campaign websites since 2000, for example, and it currently has more than 200 terabytes of webarchives.
My personal favorite use of libraries is for photographs that are digitized and up on the Web, provided from the archives of the Denver Public Library and the Library of Congress.
The Internet was supposed to be about the long tail: In 2004 Wired editor Chris Anderson wrote a seminal article describing how the Web would create limitless choice and revive interest in deep reaches of music, book and video archives.