Here is a great new feature from Google Translate for your phone. It's called Conversation Mode and it lets you use your phone to converse with someone in a different language.
In it's initial incarnation, you talk into the phone in English, and it reads back a translation in Spanish. The person you are trying to talk to can respond in Spanish and it will read the response back to you in English:
Can you imagine how useful this could be for travelers? It's only English/Spanish for now, but no doubt other languages will follow.