Category Index of Directories

Andy's Highway Kickoff Page
Large list with annotations.

California Highways: Other Links
Links to resources covering many countries.

Nationwide Interstate Links
Connects to the respective Interstate portions of other websites.

Roadfan Locator
Listing of people interested in the subject, with contact information. Organized by geographic area.

Tony's Exit List Collection
Contains exit lists for all 2-digit and most 3-digit Interstates, sorted by state and/or city.