The hottest recent launch was Wikimapia. It uses the Google Maps API and a Wiki interface. This new functionality enables users to enter or edit information with map hotspots. However, it comes with the advice not to add something that would not be generally useful. Currently, the entries mainly consist of empty hotspots on buildings of interest, but a UK PacMan was also spotted. The search functionality only works searching tags applied to entries.
As per now there are not many entries. However, it won't be late before it catches up with the public imagination and gives stiff competition to Microsoft MapCruncher.