Somewhere on the App Store spectrum, between the travel phrase books and those apps that replace your mouth with a slightly weirder mouth, you'll find iLingual, an app that steals your lips and uses them to speak three different languages.
Here's how it works: you snap a picture of a mouth - yours, your girlfriend's, or just a photo from a magazine - which iLingual then analyses and converts for animation. Then, you choose a phrase from the app's 400-strong library, hold your iPhone over your mouth and there, you sort of speak French, German or a little bit of Arabic, with a disconcertingly segmented, animated pair of lips. Félicitations!
This really shouldn't be more useful than a standard pre-recorded phrasebook, but it definitely is. Nobody likes tourists, and the genius of iLingual is that by using it, you're making fun of yourself; you're giving people something - a small amount of your dignity, or if you're lucky, a laugh - in exchange for their help. iLingual is a sponsored app, so it's completely free. [iTunes]