Here are some URL's I think everyone should know about:

The Microcar and Minicar club
www.microcar.org/ourcars.html

(you see: they make a clear distinction between 'microcars' and 'minicars' - the two words look alike a lot in English unfortunately.
In Dutch we call them "brommobielen" and "compacte auto's" which is a muych easier distinction).

and ofcourse the very, very fine
www.microcarmuseum.com
the virtual tour is outstanding!

here's a rather ugly site from Belgium but has some really unique pictures,
probably made by the webmaster himself:
bijzonderevoertuigen.f2b.be/
(scroll all the way down)
+ his Vespacar site
aapjes.f2b.be/
(scroll all the way down again)

and this is a neat one too
www.3wheelers.com/enter.html

add yours!