Aeromexico
Clearly marked deals for top Mexican attractions.

America West
Last-minute bargains, mainly west of the Mississippi.

Alaska Air
Fares only available on-line--but NO refunds.

American
Requires cumbersome login process, but American covers a lot of territory.

Continental
With registration, Continental will e-mail you current special fares.

Delta
Delta will e-mail their Wednesday morning specials. Book the ones you like quickly.

Hawaiian Air
Buy a ticket to one island, get another island hop for free.

Northwest
Their fares to Asia and Europe usually are worth a look.

Southwest
Tough to beat for domestic fares between non-hub locations.

TWA
Good deals if you can start or connect through St. Louis

United Airlines
Their "E-fares" are available only to registered users. Registration is free.

U.S. Air
U.S. Air offers a nice selection of cities for weekend getaways at low fares.   Fare Searches Alternative Airports From 1travel.com, a guide to airports that are a short drive and long savings from your final destination.

Internet Airfares
From Destinations Unlimited, this site tracks fares by major city, and has a section on "big fare cuts". Act on those quickly, because they rarely last long.

Smarter Living
Last-minute travel deals from twenty airlines.  

Air Travel
Deals, deals, and more deals, from about.com guide Linda Nelson.

Asia Travel
A guide to South Asia air travel from about.com guide Andy McCord.

Canadian Air Sites
A lengthy list of deals north of the U.S. border, from about.com guide Elke Mairs.

European Air Sites
Durant Imboden has four pages of European airline sites at goeurope.about.com.