Word Lens is an augmented reality app that can translate text from the real world, on the fly, just by looking at the text through your phone's camera. Google has had a similar solution with the Google Goggles app for a while now, but the main difference is that Word Lens can be a lot faster, and it also works offline.
This could be a lot more useful when traveling, since you don't have to worry about having a data connection when you want to translate something, wherever you are. The downside is that you the app only works with 3 language pairs by default, which are included in the $4.99 app: English-French, English-Spanish, and English-Italian. However you can buy other language packs from the Play Store.
Word Lens has been available for the iPhone for the past 2 years, first appearing on the iPhone. The developer had to make the app in assembly initially, just to make it fast enough, even for the iPhone 4. You need a lot of processing power to be able to translate in real-time like this, especially on a phone, which doesn't have that much powerful hardware. But this is the reason why we'll still need more powerful hardware in the future for our devices. Because who knows what some developers will come up with if we just give them powerful enough hardware.
The Word Lens app is now finally available for Android, although some users are experiencing some issues with it right now, so you might want to hold off from buying it for now, but you can try the free lite version from the Play Store right now.