Apps that work on iPhone also work on iPad and iPod Touch just as Android apps operate on phones and tablet devices from Motorola (Xoom) Samsung (Galaxy), archos (several models), Acer (several models) and others.
Security and networking
iHound Tracker: Monitoring and tracking app for mobile devices that will help you meet people and ensure you don't lose your device abroad. Users can program Geo-fences (i.e., virtual perimeters within a certain distance from a device) to send out alerts (through push texts, e-mails or Facebook posts) when you or a loved one is near or arrive at a destination (such as an airport). If you leave your device behind, you can log onto http://www.ihoundsoftware.com and trigger this message with or without a siren: "Stop! This is iHound. This device has been reported missing." Once iHound is activated, it can run silently in the background, so it doesn't drain your battery. $3.99 for iPhone with an initial three-month subscription for iHound's tracking service. Seven-day free trial for Android; a current special offers one year of service for $3.99 (versus $10.99 for Apple devices).
iLingual French, iLingualGerman (from Emirates): Makes language translation fun if you can laugh at your linguistic limitations. After indicating your sex, the app instructs you to take a photo of your mouth. After you adjust the image, you set the vocal pitch. Then when you need to speak French or German, you hold the app in front of your mouth and your "stylized" photo lips move while the app speaks the language for you. Phrases are organized by themes, including airport, taxi, hotel, sightseeing and general conversation. Free for iPhone.
Rick Steves Audio Europe 2011: Organizes audio files (including podcasts) into geographic playlists throughout Europe including Britain (Beyond London and London), Eastern Europe, France (Beyond Paris and Paris), etc. "Download and play whenever and wherever you like without incurring data charges," Steves said in a phone interview. "Travelers have so much downtime on the plane or waiting in line. This offers free tours that would otherwise cost $50." Other smart phones can download Steves' free podcasts without this iPhone app.
Fotopedia Heritage: 25,000 photos of all the UNESCO World Heritage Sites worldwide with about 7,800 images of Europe from the Tower of London to Prague Castle in the Czech Republic. Free for iPhone.
Staying in touch
Tango: Offers free video calls between Tango members (membership is free). During a call you can switch into audio only mode or switch video views to see what the caller is seeing around you (to give that person a better view of the Eiffel Tower, for instance). The app was designed to use as little data as possible to reduce data charges if you're using 3G and not Wi-Fi. Tango works with your phone's contact list, shows you who already Tangos, then helps invite others to Tango too. Free for iPhone and Android. Both apps work on Apple or Android devices without a camera including the iPad.
Navigon MobileNavigator Europe includes 2 and 3D map displays for all of Europe, turn-by-turn voice directions and displays nearby parking options. Works with data roaming turned off. $119.99 for iPhone and $123.90 for Android.
Presselite London Tube, Métro Paris Subway, Barcelona Subway, Madrid Subway and Moscow Metro: All provide detailed subway station and line info to plan your transportation. Each costs 99 cents for any phone platform. All work on iPhone. London Tube has versions for Android and Windows 7. Métro Paris has a Windows 7 version.