US State Department, Bureau of Consular Affairs (visas, passports, travel advisories)
XE Currency Converter
World Meteorological Organization
Distance Calculator
Travel Sites:
Amtrak
Carnival
Delta
Greyhound
Hotels.com
AirBnB
Expedia
Orbitz
Travelocity
TripAdvisor
Country Guides to Culture, Customs, and Etiquette