Google shared a new Google Labs experimental feature, "Download map area," and also two already exisiting: "Scale bar" and "Measure", today at google mobile blog.
"To access Labs on your phone, press your phone's menu button once in Google Maps, choose "More" and select Labs. On a tablet, click the menu button in the upper-right corner of Maps. The "Download map area" lab requires Android 2.1+ and the latest version of Google Maps," noted Chikai Ohazama, Director of Product Management, Google Maps for mobile.
Download map area
When you're visiting an unfamiliar location, Google Maps for mobile is great for getting an idea of how close you're to your destination etc. But what if you don't have a data signal, or you're abroad and don't have a data plan?
"The "Download map area" lab in Google Maps 5.7 for Android helps work when you're offline. Before you take your trip, while you still have access to WiFi or data coverage, you can open up any Places page in the world, click "More" to get the Place page menu, and download Google's maps for a 10-mile radius. The download can take as little as a minute or two. This download stores only the base map tiles and the landmarks on the map, so you still need a data connection to see satellite view and 3D buildings, search for Places and get directions.
All your downloaded map areas can be managed in your Google Maps cache settings so you can delete maps you no longer need or if you want to free up storage. After 30 days, all downloaded map areas will be removed from your cache; they can be re-downloaded any time," explained Ohazama.
Google Maps has approximately 20 different zoom levels that range from a 2,000 mile scale to a 20 foot scale. With finger gestures making it really quick and easy to zoom in and out, sometimes it's not always clear what zoom level you're at. What might be just a few streets away can be quite a long walk depending on the scale. To help with this, you can turn on a scale bar, which updates based on your zoom level.
Measure can help you know the distance between any two points on the map. Once it's enabled, you'll notice a tape measure icon just above the zoom buttons. After clicking that icon, you'll be prompted to tap two points on the map and Google Maps will calculate the straight distance between those points (this direct distance is "as the crow flies").
Example of the "Measure" Labs feature:
[Source: Google Mobile blog]