The White House home page provides Presidential Speeches and Remarks, the Weekly Address, Statements and Releases, and Press Briefings. See also Proclamations, Presidential Memoranda, and Executive Orders.
Compilation of Presidential Documents Available on FDsys, "The Compilation of Presidential Documents collection consists of the Weekly Compilation of Presidential Documents and the Daily Compilation of Presidential Documents which are the official publications of materials released by the White House Press Secretary. The Compilation of Presidential Documents is published by the Office of the Federal Register (OFR), National Archives and Records Administration (NARA)."
A Guide to Presidential Documents and Presidential Libraries of the National Archives and Records Administration
Resources of the National Archives of the United States.
Online Index to U.S. Presidents
Inaugural Addresses of the Presidents
Avalon Project at the Yale Law School
Inaugural Addresses of U.S. Presidents
State of the Union Messages (American Presidency Project)
POTUS (Presidents Of The United States)
Presidential Papers (University of California, Berkeley)
Presidential Papers, Speeches, and Executive Orders (University of Oregon)