This app uses the iPhone’s geo-location functionality to provide audio guides for wherever you may be. Its developers say that HearPlanet is like having a professional tour guide with you at all times. The truth is, it's great for popular tourist destinations, particularly American ones like The Grand Canyon where the app will provide a professional sounding guide. For places that aren't yet loaded into its database, the guides sound more like Stephen Hawking reading straight from Wikipedia. Still, there are 250,000 locations with the proper guides already and the list is, apparently, growing. (HearPlanet, £2.99)