Postage stamp collecting

Poststukken & Poststempels
Site in Dutch of a collector group based in the Netherlands interested in Dutch postal history and cancellations

Brunswick Philately.
Site devoted to Postal history, stamps and postal rates of several (former) German states, such as Braunschweig (Brunswick) in particular, and Dutch potsal history

Klaver, T - Filatelite
Site in Dutch, with galleries and articles about Dutch postal history