Yellow Chairs

This sounds like a more sociable alternative to warchalking – you place a Yellow chair outside your house and invite others to sit on it to share your wireless network.
This is an interesting art project, its worth reading the background story
The person who set this up appears to have found that theiir network became too slow to continue with the fully open service, but it does offer some interesting insights into social interaction.
There is another article about this on http://www.we-make-money-not-art.com/