Expedia.com
A major booking site with negotiated discounts and e-mail alerts on fares.

FareChase
Combs through more than 80 online discounters searching for deals.

Qixo
Searches dozens of discounters and airline sites for the lowest fares.

SideStep
Scans dozens of airline, hotel and car rental sites for discounts straight from the supplier. First you have to download SideStep's software.

Orbitz
Airline-backed site shows many flight options by carrier and number of stops on an advanced grid.

Travelocity
A leading all-around booking site with negotiated discounts and e-mail alerts on fares.

Cheap Tickets
A discounter ticketer - sometimes it's easier to find bargains by calling the toll-free phone number.