Advisories and Documents
Foreign Entry Requirements
Passport Services
Travel Warnings and Consular Information Sheets

Airfare, Online Ticketing
Expedia
Kayak
Orbitz
Travelocity

Airlines
SeatGuru: Airplane seating information, etc.
Yahoo! Airlines

Books and Guides
Backpacker
Fodor's
Frommer's
Hidden America
Let's Go
Lonely Planet
Places OnLine
Road Trip USA
Roadside America
Rough Guides
World Travel Guide

Camping and Lodging
BedandBreakfast.com
Camping
Hostels: Hostels.com and Hostelling International
Hotels

Currency Converters

General Travel Sites
Tourism Offices Worldwide Directory
The Travel Channel
Yahoo! Travel

Health
Shoreland's Travel Health Online
Travelers' Health -- Centers for Disease Control and Prevention

Hiking
GORP: Hiking and Backpacking Guide
LocalHikes
Trails.com

Parks and Recreation
Federal Lands
Florida State Parks
National Parks
Park Search: United States via L.L. Bean
The Official State Park Pages

Phrasebooks, etc.
TRAVLANG: Travel and Language

Travel Deals
TravelZoo

Travel Tips
Culture Crossing: A guide to cross-cultural etiquette