Geolover is a nice travel guide for tourists and travellers that uses the Google Maps API. You can use Geolover to find popular tourist destinations around the world and build your own travel guide, which can then be accessed from your mobile phone.
To use Geolover you can just zoom the map onto a city and the most popular tourist attractions in that city will appear on the map. You can then browse through the points of interest, read the location's entry from Wikipedia, view videos from YouTube, view photographs from Flickr and read tips from Foursquare.
If a particular tourist attraction take your fancy you can then add it to your 'My List'. When you are satisfied with your list you can then create your own travel guide and map and save the link to your mobile phone.