Arnold Krille wrote:
  If you didn't sign a contract and work on a
project, the
 copyright is still yours 
Are you sure? I guess (and I'm not sure) that if you did some kind of
work, e.g. being a developer for a company, it implies that the employer
will take on the copyright and that you aren't allowed to disclose
know-how, even if there isn't a special contract saying this. If I'm
wrong, this  would give me some thrilling views for my future, because
of my past and especially a friend could benefit from this, because he
did much more for other people than I did.