Schemer - Users leave recommendations for things to do in their city and visitors can add to a to do list and check off as they go.
TripAdvisor - Honest reviews of hotels, restaurants, attractions, and more.
Instagram - Coverts photos into works of art. Instagram gives photos professional, antiquated, or artistic looks. It makes sharing pictures across social media networks easy.
Groupon - Find 50% to 70% off restaurant offers.
mTrip - Provides travel guides around the world, offline maps & navigations, personalized itineraries of visits, and trip journal and sharing.
FourSquare - Turn on this app upon arrival and see a list of tips from those who have been there before you.
HopStop - Offers public transport information on 68 of the world’s biggest, busiest metropolitan hubs.
World Clock - Time Zones - provides easy access to the time in hundreds of cities and adding several clock as home screen widgets.
Livingsocial - Find 50% off restaurant offers.
EveryTrail - Track, share and explore.  Plot your trip, photos, and video right on the map and upload it to EveryTrail, Facebook, and Twitter.
Where To? - Enables user to locate almost anything nearby, including the nearest ATM, burger joint, and medical provider. 
Ski & Snow Report - Get the latest ski reports with detailed trail maps.
PhotoSynth - Enables users to take awe inspiring panoramic pictures in an instant and is fully integrated with Facebook.
Yelp - Find places to eat, shop, drink, relax, and play and read reviews from knowledgable locals.
JetLag Genie - Gradually alter your sleep habits before a trip to better deal with jet lag.