If you don't read http://blog.jonudell.net/, you might consider adding it to your blogroll.

Of interest is one of his latest posts on how Facebook wants to know how you’re connected to people, and how one seemingly logical choice is missing...

"Like other social applications, Facebook wants to know how you’re connected to people. So it asks: "How do you know this person?" ...  

The choice I usually want — "Through the Web" — isn’t available. One friend coerced “Met randomly” by adding "The web as a conversation engine" — but that’s an unsatisfactory workaround. There was nothing random about how we met. Given our shared interests and our online expression of them, it was inevitable that we would come into contact.

"Through the Web" should be a first-class answer for "How do you know this person?" 

I'll reckon, it's difficult to know anyone "through the web." You can stumble upon or find people through the web, but you come to know them through interaction as a result of an introduction via the web. And as the cartoon that my old boss (shameless name drop), Trip Hawkins, shared with me one afternoon far too long ago calls out "On the Internet, Nobody Knows You're a Dog."

So, perhaps the question is better put: "How do you know this canine?" ;)