A good overall source for computer and technology information.
New York Public Library's free, online, searchable database of 275,000 photographs and manuscripts.
Dictionary that allows you to research a non-alpha-numeric symbol and find what it stands for.
Prints and Photographs
The collections of the Prints & Photographs Division include photographs, fine and popular prints and drawings, posters, and architectural and engineering drawings. While international in scope, the collections are particularly rich in materials produced in, or documenting the history of, the United States and the lives, interests and achievements of the American people.