Library of Congress
The Library of Congress has a wealth of information, including their
on-line catalog and a number of other institutions through a "Z.39.50"
gateway as one of their "Library Services." They also offer an
extensive set of links to other resources (the economics-oriented
ones are generally described elsewhere here) and substantial
information on the U.S. Government, including Congress. It appears
one can use their photocopy service long distance.