Wim and I live in a condo which is good for two working people, but then you also have the rules of the condo association to live with.  Here are a few of the signs we see on the common greens.  We are greeted with a speed limit sign and a reminder to sales people which we don't mind.  There is a tennis court for us to use, but you see very few people on it.   We have a little play area for the children, but we have a private property sign because community children were using it (I don't see why they can't.)  There is a odd number sign to help you find places.  
By the mailboxes there is a parking sign so that people can get to there boxes.  And so that in case of a fire, we have a  hydrant sign so that the firemen can find the hydrant which is hidden by the bushes.

(The thumbnail is not on the condo green.)