

The Library of Congress presents the National Jukebox, which makes historical sound recordings available to the public free of charge. The Jukebox includes recordings from the extraordinary collections of the Library of Congress Packard Campus for Audio Visual Conservation and other contributing libraries and archives.
IMSLP now has a search-by-melody function...
http://imslp.org/wiki/IMSLP:Search_by_Melody
The Visual Arts
Los Angeles County Museum of Art makes their collection available online !
The Museum website is here http://www.lacma.org/
Their digital collection is available here http://www.lacma.org/art/ImageLibrary.aspx
Yale University has done the same thing
Digital Images of Yale’s Vast Cultural Collections Now Available for Free
read about it here
http://opac.yale.edu/news/article.aspx?id=8544
there's a slideshow sampler about halfway down the page.
The link to their frontpage search box is http://discover.odai.yale.edu/ydc/