And it's worth noting that Leviathans was published under a Creative Commons licence. Feel free to share the rules and other e-supplements you have - with suitable attribution (eg. don't hack off the CGL trademarks), and of course never charging for them.
(Note: does not cover minis. However, I think we're reasonably free from the sort of IP theft affecting some companies we share IP with. OTOH, if someone did want to make Leviathan minis ... talk to me O0)