I wish this was available as a translation app. You point your phone at a fruit stand and it names every single item, and you can then ask the vendor for the item by name.
It isn't that crazy, in fact that's exactly what they have right now but just in English only.
Not exactly what your'e talking about but you should take a look at Word Lens(which google just bought).
Basically you hold your phone up and position it over a piece of text using the camera. It then OCRs the text, translates it, and replaces it in realtime in the camera feed. It's pretty remarkable.
It isn't that crazy, in fact that's exactly what they have right now but just in English only.