I've listed 25 start-up maps that I know about here. I'm sure there are many others.

http://googlemapsmania.blogspot.com/2014/03/25-start-up-maps...

This can only be good news for wikmapia. http://wikimapia.org/

At one point wikimapia was the most popular map built upon the Google Maps API. I'm pretty sure it's why Google introduced a wiki layer themselves to Google Maps.

Google Maps Mania posted about a few similar maps last week.

As well as the Netherlands map there is the Portland map, a map of Ljubljana, Slovenia (similar to the Portland map) and the Brooklyn map.

http://www.mapsmaniac.com/2013/08/view-age-of-10-million-glo...