I've got several questions that I want to wrap into one. I'm curious / concerned about sister sites. For example, I have the following domains:

www.example.org - my main site
m.example.org - My mobile site
tab.example.org - My table specific site
example.xxx - A 'version' of my main site, but with 18+ advertising

How can I let search engines know these are all the same site? For example, sometimes when I do a search on google, from my phone, I'll get results that are all or mostly other mobile sites. All of the domains above will have the same url structure. Is there a way to say, "this url is the mobile version of this authoritative url" ? And what about the xxx site? It's going to be more or less a full on clone of the main site. I know I could block indexing with it's robots file, to make sure it doesn't end up coming up in search results. For any traditional search, I'd want the main site to show up.

And lets not forget that tablet site. I'm going to do some unique styling and navigation that will make things easier and more fun to use on a tablet. But it's still more or less going to be a clone of the main site. But "tablet" (and "#*$!" for that matter) are not official media types. Also, I believe I remember from a long time ago, that google would punish identical sites, if you were to make a million copies of a real site, under real domains, and try to just flood the market. I don't want to do that either.

What do you think?