Google has updated its Android Maps application with the ability to store offline mapping and location data [bbc.com]:
Google has upgraded its Android Maps app so it can provide directions when not connected to the internet. The software also lets devices find businesses' locations, opening hours and telephone numbers while offline. The firm said tourists visiting places outside their mobile subscription plans and people living in emerging markets, where data can be expensive, would be among those who would benefit most.
But one expert said budget-phone owners would now have to juggle data. "Entry-level Android smartphones sometimes only have four gigabytes of onboard storage, making it a precious resource," commented Ben Wood from CCS Insight. [...] Google said downloading most of Greater London would take up 380 megabytes on a device, while storing the San Francisco Bay area would require about 200MB.
It allows you to define a rectangular area specifying the mapping data you want to have available offline.