Thanks to some rather liberal legislation it has never been that hard to find fun things to do in the Netherlands. However if do find yourself at a loss for something to do in the country then Leukedingenkaart has lots of suggestions.
Leukedingenkaart is a real-time searchable Google Map of upcoming events in the Netherlands. Leukedingenkaart scans Twitter for events and displays them on a map. If you are looking for something to do in your area you can just drop a map marker on your location and the latest events will automatically be displayed on the map.
You can define a radius for the maximum mileage you want to travel and you can also filter the events by entering a search term.