Not that advertising another forum here is particularly good
form, but I would recommend TankNet to anyone who is
interested:
http://63.99.108.76/cgi-bin/ubbcgi/Ultimate.cgi
The forum was started by a group of American armour enthusiasts,
but it has since expanded to cover other military subjects. It is
still quite American in outlook, but there is a fair contingent of
Europeans, Australians and Israelis to keep the balance (in fact,
at any given moment, there is usually at least one heated debate
about the Middle East carrying on). Some of the posters there have
a stunning degree of knowledge of military subjects; one of them
has publised a few books on the history of firearms. About half of
them have had military experience, and some of them have worked on
interesting projects. If I recall correctly, there was one poster
who was an engineer on the B2 project.