There used to be a time when vacationers picked up the phone, called their travel agent and kept their fingers crossed, hoping for a great deal on a flight. If you were lucky enough to get a discounted rate, that was wonderful. If you had to pay full fare, well, you weren't going to cancel your vacation over it. Just as computers have changed the way the world operates, they've also turned Joe Traveler into an armchair travel agent. Today it's possible to check flight availability, search for the best fare, book your own flight and in some cases, even choose your seat on the plane - all at the click of a mouse.

The advantage, of course, is the ability to compare air fares offered by several different companies within a very short time span. There's no phoning around, no automated messages to contend with and the information is right in front of your eyes.

There's no waiting for the travel agency to open at 9 a.m. and no cursing when you realize they closed at 5. When you wake up at 2 a.m. with an urge to fly to Orlando, you simply fire up the computer and book your flight online. Thanks to easy-to-follow instructions, the Internet helps you access virtually the same airline timetables, ticket prices, routing, seating information and restrictions details as a professional travel agent.

But anyone who's ever surfed the 'Net knows that it can be a time-consuming process - unless you know exactly what you're searching for. That's why we've come up with this handy, concise list of Web sites that promise low airfares to many popular destinations. Though a computer isn't a substitute for a knowledgeable travel professional, it can give you - the consumer - the inside track on where to find some really great prices.

Keep in mind that a well-designed online travel site should let you access the same information you'd receive from a travel agent. This includes finding and booking flights; comparing prices, seats and routings; researching destinations; tracking flights in progress; offering information about discounts and incentives; and keeping consumers updated on travel news and events.