In The Netherlands, there's a lot of info available on things to do with your kids. One example is Museumkids, a website by the association of museums, showing what's available in museums. Kids can even send their "inspection report" to improve the info.
Another example is Kidsproof, a website curated by parents, combining all sorts of things to do, clubs, places to eat and so on, in a specific city or region.
There are several others like this. Several cities and municipalities also have information available, both online and offline.