If you look at my LinkedIn account, it would seem like I'm not a particularly active user; I've only got 79 74 connections and no picture. Here's the thing: I'm not sure if I'm using it right.
My LinkedIn 'friending' policy is simple: I'll accept a connection if the person offering it is somebody who I would feel comfortable recommending if somebody asked "hey, do you know any good ____?" Unless I've worked with somebody, am personally friends with them, or have had the kind of conversation where I can sort of smell competence, I probably am not comfortable being a LinkedIn connection of theirs.
There's a reasonably good chance that I'm wrong. My friend Yujin, an MBA who now does bizdev for Venture Capital, says I should be friending most business connections I make and that this is the norm for LinkedIn. As a result, Yujin's got 500+ connections and is the ultimate connector. And he rocks it. Still, I feel uncomfortable with the idea of being a connection (and, effectively, agreeing to be a reference for) somebody who I don't yet trust.
LinkedIn seems to at least somewhat agree with me on this; when I try to add a new contact, it warns me to add only 'people you know well and who know you.' And yet, I've had a number of (reasonably respectable) random people add me as a LinkedIn connection as a way to get an introduction. There's a reasonable chance that this is because they can't find my email address and LinkedIn tries to make money by offering 'direct contact via inMail' as a premium feature.
One solution to the whole friending strong versus weak ties (which, esp. when compared to Facebook's or Twitter's, probably deserves its own post) is LinkedIn's endorsements feature. If you really want to show that you trust somebody, endorse them by writing a positive recommendation. Still, I can't bring myself to 'accept' people I would not (yet) comfortable hiring or working for.
It would be nice to have a social rolodex where I can can add anybody I've ever met, without any implied friendship or any fears of references or privacy. This is almost what Twitter is, except that I'm not particularly interested in what random people I've met once have had for lunch. What I would (ideally) like is a social, digital rolodex, sorted by time and (perhaps) with some sort of tagging features, so I can mark people by the things we share in common.
Perhaps I'm just old-fashioned. What are your LinkedIn 'connection' policies?