Any material produced by me is covered by a Creative Commons Attribution-Share Alike 3.0 License. It may therefore be copied for personal use and freely reproduced, in any media, provided the source is cited. However, you may not reproduce it without acknowledgement (it's bad manners, if nothing else).
No original material produced by me may be used for profit – including being reproduced in a book, magazine or web-site – without written permission from me (which I will generally be happy to grant, if you ask nicely). "For profit" includes any book, article or web-site for which payment is received or which earns advertising revenue.
"Produced by me" includes translations – even if there is no copyright on the original material in the original language – and revisions of original maps.
The copyright for anything supplied to me by someone else remains the possesion of that person – you have permission to download it for personal use only.
If I have credited any material as being produced by someone else you may not reproduce it in any form, in any other media, even for non-profit purposes.
The Soviets renounced copyright, so any material from the former Soviet Union, Soviet Poland etc is free to be reproduced by anyone.
Some other material on the site may be in copyright – it's a bit hard to track down who owns these things when the author is long dead and the publisher no longer in business. If you can show that you do in fact have copyright to material, I will remove it immediately.