Social networks for neighbourhoods

[Summerinthecity 47]

What do you think of the social networks for neighbourhoods which are now founded all over Germany ( wirnachbarn.com, nebenan.de etc. )? Do you think it is a good idea? Do you have anything similar in your countries and are there any cultural differences?
As regards myself, I am a member of such a community in Duisburg Neudorf and I only made positive experiences up to now. 99,9 % of all users are much more polite with each other than on Facebook, and I also have the impression that they are very helpful and sociable.