History Matters gateway to historical sources on the net. Recommended.
USA.gov - Search government documents.
Florida Memory Project - Lots of primary sources for Florida topics.
Documenting the American South - (DocSouth) is a digital publishing initiative that provides Internet access to texts, images, and audio files related to southern history, literature, and culture
American Heritage Magazine - Includes some searchable full text content. Not scholarly.
Primary sources on the Internet - Written by the Instruction & Research Services Committee of the Reference and User Service Association History Section in the American Library Association.
NARA Presidential Libraries and Museum Page - provides selected primary resources and also explains how to research presidential documents.
Library of Congress - Primary digitized documents from American History and related collections.