Google Translate has been around for a while, and they just got an important update for both iOS and Android devices. It's also getting much better.
For instance, there's Word Lens, which lets you snap a photo of text and gets in translated in 36 languages which has been updated to translating text instantly be pointing your camera at a sign or text.
The translation feature is limited to English, French, German, Italian, Portuguese, Russian and Spanish for now.