Knapsack - Plan your trip and later share memories.
Evernote - Take notes, capture photos, create to do lists, record voice reminders, and make these notes completely searchable. Users can combine and share travel notes.
Packing Pro - Enter destination, length of trip and who with and it will provide a list of what you may need.
TravelSafe - A database of emergency service and embassy phone numbers for almost every country.
Groupon - Find 50% to 70% off restaurant offers.
FlightAware - Track your flight by entering your airline and flight number and receive updates on flight delays, gate changes, and/or cancellations.
Touchnote - Send real postcards using cell photos.
Zagat - A guide to discovering the best restaurants, bars, cafes and clubs.  Started with nine cities (Austin, Boston, Chicago, London, Los Angeles, New York, Philadelphia, San Francisco, Washington DC) with more on the way.
RoadAhead - Find the best exit ahead on the highway to meet your travel needs.
Google Goggles - Search by taking a picture. Users can point their cell phone cameras at paintings, famous landmarks, barcodes or QR products, or popular images. If Goggle finds it in its database, useful information will be returned.
TripAdvisor - Honest reviews of hotels, restaurants, attractions, and more.
Yelp - Find places to eat, shop, drink, relax, and play and read reviews from knowledgable locals.
AlpineQuest GPS Hiking - Comprehensive orienteering maps come complete with contour lines.
Tripit - Combine all your travel reservations in a single locations.
Urbanspoon - Shake your phone and the Urbanspoon slot machine will suggest local popular east via the GPS in your phone throughout the US, Canada, UK, and Australia.