This is so cool! I did a similar thing in ASCII on my BBS many years ago and have always been thinking of doing it with graphics for the web but have never gotten around to it. Now I don't have to if you release this! =]
Things I was thinking of having on my version:
- User can click where they want the graffiti to be.
- Only showing the latest graffiti, as you mention.
- Possibility to select color and maybe font.
- Letting the admin remove graffiti.
