I just love maps. I always have. I used to spend hours with the Delorme Street Atlas CD-ROM until the company dropped Mac support. Of course the CD map business is mostly dead with online maps and easy access from computers, smartphones, and tablets.
Recently, I've spent some hours with a free universal iOS app called Recce-London. It is a rendered 3D map of central London, and will be great for visitors to the Olympic Games. The app lets you explore London; you can find restaurants, transportation, landmarks and more.
The graphics are reminiscent of SimCity. You can rotate the 3D view, and zoom in and out. In addition, there are realistic traffic sounds, and you'll see animated cars, trains and even boats navigating the Thames River. Although the cars and boats are really just eye candy, if there is an accident you'll see it noted on screen.
The amount of data is really quite prodigious, but the maps are onboard your iOS device, while traffic info and updates to locations are coming in as over-the-air data.
The app is provided by eeGeo, and the company has said more cities will be added, with versions coming soon for San Francisco and New York. The only negative I found with the app is I'd like to be able to shut off the city sounds, which in a short time beome a distraction.
Recce-London (Recce is British slang coined in 1941 as an abbreviation for reconnaissance) is fun to explore and for free I suggest you try it. The app is universal for iOS devices and a large download, 125 MB.
There's an FAQ about how the app works and what it does on the web.