Google Translate: Translates words and phrases for 57 languages but requires Internet access. Superior speech recognition: Say a word or phrase, then hear or see it written phonetically in the target language. Free for iPhone and Android versions.
Jibbigo Japanese English Speech Translator: Works offline without Internet access, but the speech recognition function doesn't understand American English as well as Google Translate does. When I asked, "Where's the toilet?" the app translated it as "Prayer is in twilight." Speaking slowly helps, and Jibbigo does request feedback about speech recognition errors. $27.99 for iPhone and Android versions. Also Jibbigo Chinese English Speech Translator, $24.99 for iPhone and Android.
Lonely Planet Mandarin Phrase Book: Popular phrasebook helps travelers navigate Mandarin with almost any smart phone. $5.99, for iPhone, Android, BlackBerry, Windows Mobile and Symbian.
Lingopal 44: Talking phrase book with 44 languages, including Cantonese, Mandarin and Japanese. $9.99 for the iPhone. Also Lingopal 42 (lacks Hindi and Bengali), $10.11 for Android.
Broadspeak Translator: Translates more than 50 languages. Free for Android.
Kotoba! Japanese Dictionary: Multilingual Japanese dictionary app offers quick access to words and phrases. Free for iPhone.
Human Japanese: Offers a gentle introduction to learning Japanese with quizzes and recorded words and phrases. Basic version is free; full version is $9.99 for iPhone and Android.
Mobile Maps Southeast Asia: Turn-by-turn voice navigation in multiple languages, including English. All maps are inside the app, so the only data roaming charges will come from using your phone's GPS. $39.99 for iPhone, Windows Mobile and Symbian; different versions and prices for Android.
Asia Subway Maps: Map apps from http://www.exploremetro.com for navigating subways in Shanghai, Beijing, Guangzhou, Hong Kong, Singapore and Taipei, Taiwan. Apps offer info in English and Chinese and include a route planner and Google Maps for every station. Taipei is free for iPhone; all other cities $1.99.
mTrip Apps: Individual city guide apps for Beijing, Shanghai, Singapore and Tokyo help you plan your trip. The mTrip Genius builds an itinerary based on your choices and whether you prefer museums, monuments, parks, etc. Hotel, restaurant, shopping, night life and transportation info also included. $5.99 for the iPhone and Android.
GPSmyCity Apps: Map and walking tour apps for many Asian cities, including Bangkok, Beijing, Hong Kong, Saigon, Shanghai, Singapore and Tokyo. Uses GPS and Google Maps to guide you from place to place. Basic version is free; $4.99 (full version) for the iPhone and iPad 3G.
Travelfish Angkor Wat, Cambodia: The free app is loaded with lodging, food, attraction and historical info. For a trip to Cambodia, I would spend $5.99 for the fully loaded version, which includes a Siem Reap guide and more accommodation listings. Travelfish also has iPhone apps for Laos, Thailand and Hanoi.
Love Indonesia: All-in-one app covers restaurants, hotels and more for 16 cities in Indonesia, including Jakarta and Bali. Free for BlackBerry only.
Nomads Path Asia Guide: App covers 12 Asian countries, including China, Japan, Mongolia, Taiwan, Cambodia and Indonesia. Free for iPhone.