With the retirement of longtime Librarian of Congress James Billington, the next Librarian has big decisions to make that could revolutionize the world's largest library by bringing more of its collections to the Internet. The Atlantic has written a great article on the possibilities that await, and could potentially transform the Library of Congress into a true national library. It also provides a good overview of some of the Library's successful online collections, such as congressional records clearinghouse Thomas (which recently evolved to Congress.gov), and the Library's historically interesting Print and Photographs Online Collection.
Other challenges await, such as the Library's long gestating project to archive Twitter, which was announced in 2010 and built as of 2013, but has yet to be made searchable by researchers and the public.
The Atlantic also provides a good overview of other libraries' ambitious digitization and online collection projects such as Hathitrust, Trove, and Europeana.
Library of Congress Main Reading Room, Thomas Jefferson Building, Washington, D.C.