Ok thanks guys!
I ask because of google. I know if sites with sequential IP addresses link to each other, they are penalized or possibly spam filtered if there are many of them in the same topic.
So, I'm guessing google is okay if I link my sites up to each other (naturally - not in a way to spam) then I won't get penalized...
Thank you, expecially you notjoe, you seem to know your shit!