Directories
These are websites that have links to other websites that have been evaluated and deemed reliable.
Best of History Websites
Really helpful.
Intut 
Brit site no longer being updated but there is still a lot there.
Fordham Internet Modern History Sourcebook
Very useful. Lots of primary sources. Highly recommended.
Virtual Library of Labour History
Brit site. Lots of labor (or labour in this case) and business links.
Histor esearch
Pretty good.
World wide Web Virtual Library
Italian site that is being maintained and updated.
Links to State Digital Archives
Here you can search nearly every state's digitized archives.