I just released Wikivoyage Offline, an Android application that contains guide books for 27,000 destinations.
Instead of carrying a heavy guidebook that shouts "I am a tourist", just use your phone!
Content is downloaded to the phone's SD card, so you can use it offline (useful in case of no Internet or expensive roaming).
The whole world is a 80MB download.
Content is updated every two weeks, from Wikivoyage, the "Wikipedia for tourism information", which graduated from beta last week.
The app is free and open source.