Neat idea! I love how the map is user generated. You should add a point system to it somehow.

Could you point me in the right direction for beginning to create a full screen javascript webapp like that?

A point system… I could add a leaderboard showing the people who have drawn the most tiles. But I worry that that would create an incentive for people to make lots of blank tiles. Do you see it differently?

As for making web apps like this- Do you want to make one with a scrollable tiled thing like this?, or something else?