Velorama bicycle museum, Nijmegen, Netherlands. Best museum in Europe.
Dutch veteran bicycle club. Includes a very good internet forum.
The wonderful British bicycle museum in Llandrindod Wells
The British Veteran Cycle Club. Members get access to an enormous collection of bicycle catalogues and articles.
A nice little classic bicycle shop in Den Bosch, Netherlands.
The best site about Dutch bicycles. In Dutch, German and English.

The Velocipede Gallery
Glenn Eames' wonderful collection of old pictures and old bicycles. 

Sterba Bicycles from Czech
Hundreds of antique bikes and I really love their pictures. Where do they get these jewels from?