General Travel Sites:
All of the major travel guidebook publishers have websites, such as Fodor's, Frommer's, Lonely Planet, Let's Go, Rough Guides, etc.
http://www.ricksteves.com/ Rick Steves of PBS fame offers not only a variety of tour packages but lots of good advice.
http://www.tripadvisor.com Trip Advisor: find newspaper and magazine articles, guidebooks and user comments that tell you about the ins and outs of most destinations.
Country Specific Sites:
http://www.towd.com/ Tourism Offices Worldwide Directory: A listing of official travel web sites for most states and many countries around the world. Examples:
Specific Events: a well designed event website will help you with your travel plans. For example:
Currency Exchange Rates:
Oanda Oanda, a great place to not only find the current exchange rate, but the rate patterns over time.
Which to use: Travelers Checks or Cash or ATM? Credit Card or debit card?
Check with your financial institution before you leave: to let them know about your trip and to ask if they have ATM agreements with any bank system in your destination country..
Kayak - Kayak wide variety of airlines, email price alerts
Expedia - Expedia: started by Microsoft but just recently became its own company.
Travelocity - Travelocity: owned by Sabre Holdings, a large travel agency.
Orbitz - Orbitz: developed by five major airlines: American, Continental, Delta, Northwest and United
Opodo - Opodo - created by nine European airlines
http://travel.yahoo.com/ - Yahoo Travel has been around for a number of years.
Hotwire - Hotwire: cheap tickets but you don't know who they're with until after you pay.
Priceline - Priceline: name your price and see if it's accepted.
http://www.bestfares.com/ - Best Fares: Tom Parsons' discount travel site
http://www.qixo.com/ - Qixo - a meta-search airfare site
http://www.cheaptickets.com/ - Cheap Tickets
http://www.cheapseats.com/ - Cheapseats
http://www.flightcoordinators.com/ - Flight Coordinators - great prices for tickets to international destinations
Specific Airlines Sites, such as:
Delta, Alaska, etc.
You can only book a Southwest Airlines ticket on their website
MapQuest - MapQuest for USA directions
http://maps.google.com/ - Google Maps
Tip: For traveling in other countries, you might save money by using a travel guidebook to find the names of the main local car rental companies.
Hotels.com - Hotels.com
http://www.placestostay.com/ - Places To Stay (in 6 languages)
http://www.lodging.com/ - Lodging.com
http://www.quikbook.com/ - Quikbook (US & Canada rooms only)
http://www.travelweb.com/ - Travelweb
http://www.statravel.com/ - STA Travel: the world's largest student travel organization (formerly Council Travel)
www.studentuniverse.com/ - Student Universe
http://www.elderhostel.org/ - Elder Hostel - educational travel
www.aarp.org/travel/ - AARP - for those over 50
www.eldertreks.com/ - ElderTreks - small group adventures