Communication with people you don't know

My previous post "How's my driving?" made me think of the difficulty we have in communicating with people we don't know. A website might just be the way to solve that. People could post messages based on a group they make up e.g.

• To people who catch the N35 bus
• To people who vote republican
• To people who like chocolate

Preset groups could be made and the types of preset groups would be expanded upon based upon the desires of the site's users. Groups could be based on organisations, streets, parks, trains, hobbies, TV shows.

So how would you find what posts to look at? You would enter your details (confidentially) to the site (e.g. address, company, interests) and using categories, the most relevant posts to you would flag up when you log in (or digest via email). e.g. if you entered a New York address, all posts that were "To: The inhabitants of New York" would flag on your account.

Of course, this site would allow anonymous posting so people would not be afraid of posting controversial questions.