Most initiatives in the Netherlands, as well as data sources and mash-ups are driven bottom-up. Some departments are actively experimenting with open gov data (Ministry for the Interior, Min for Education). The approach is network driven (connecting and supporting change agents).

To do
Mash-up: Widgets Min Interior
Data sources: the list at http://opendataoverheid.nl/
Initiative: guide for civil servants at http://vrijedata.nl
Mash-up: http://openhandelsregister.nl/
Mash-up: RDW Android App
Mash-up: garbage collection data.
Mash-up: ikregeer.nl
Data source: http://www.provinciaalgeoregister.nl/georegister/ (provincial geo data)
Data source: http://brabant.esrinl.com/download/ (provincial geo data Brabant)
Mash-up: http://casper.frontier.nl/ airplanes within Schiphol's area of control