I connect with most of my friends online. I've never even met some of them IRL, but we've been talking for so many years on various websites and blogs that it doesn't really matter.
I share my 3-D (cool phrase, Zerbie
) friends with my SO. There is one couple in particular that we both really like, probably because they're even bigger sci-fi nerds than we are.
We get together with them to watch movies, etc a few times a month. They don't feel like family yet, but it's getting there.
Although I do think I may be more attached to SO's siblings than he is. It probably helps that they're fellow females who are roughly my age.