The latest version of Google Maps for iOS released yesterday brought a number of new features. The most notable addition is support for the iPad, but there's also a really cool easter egg Google added into the app. The easter egg allows you to cache maps for offline use inside the app. It has actually been available in the Android version for a while, but this is the first time it has made its way to iOS.
To cache your maps for offline use, first zoom in to the area of the map that you want to save. Be careful you aren't trying to cover an extremely large area or else this trick won't work. Once you've zoomed into an area you want to save for offline use, tap on the search field and type "ok maps." Then tap the search button on the keyboard to start downloading your offline map.
If you've zoomed in far enough, you'll then see the Google Maps icon briefly appear onscreen and then at the bottom of the screen a black bar with white text will appear displaying a message that says, "The onscreen map has been cached."
After the map is cached, you can access it by simply navigating back to that portion of the map at any time. This trick is immensely handy for people with WiFi-only iPads and iPod touches, as they'll be able to be out and about with no internet connection and still see maps of areas important to them. This trick is also handy for those with 3G connections since cached maps will load faster and save roaming data charges if, for example, you are traveling in a foreign city.
Google Maps for iOS is a free download.