Just saw that Fodors.com has made its travel guide apps for your smartphone or tablet [mine being iPhone & iPad] has made them freely available = http://www.fodors.com/mobile-apps/ – another great source is Triposo [found in iTunes]
Good plan for traveling: go to iTunes Store [maybe others if they have similar offerings] and search [1] apps, [2] Podcasts and [3] iTunes U – you can find all sorts of free information about wherever you are headed.