To go beyond cars and Photoshop, the RPG Guild Wars is a good example of only loading what you need. In fact, it doesn't even download the other game zones before you need them. If it sees you running towards the next zone, it begins a buffer in the background to pull in the data. So instead of making you wait while the game downloads and installs everything right up front, it downloads then loads up exactly what you need. This is much harder in an application, which is more non-linear.