Google is offering users a new way of building maps, opening up its mapping tools for public use. You're able to edit existing data, or add your own routes, tacking unreported footpaths into Google's database, populating places of interest, filling in building detail and more.
Once you've created something there's an approvals process to go through before stuff goes live, so you're not able to be overly silly and populate the moors with genital-shaped pathways. Well, you can, but you'll have wasted your time. [Google]