Go to http://www.playstation.com/psp-app/sensme/en/download_pc.html to install SensMe
A digital walking map for the whole of Japan. It uses, but does not need the GPS accessory.
Your PSP needs to be set to a Japanese locale to see the app.
Go to https://wowroms.com/en/isos/playstation-portable/x-radar-portable/34705.html to download (107MB)
Digital Comics (OBSOLETE)
Sony closed the service on October 30, 2012, and has long since removed the application.