From the Wikipedia entry on Linked In:
It is not possible to remove yourself from LinkedIn. Instead, you have to file a customer support ticket.
This blurb neatly summarizes everything that's wrong with the Linked In service.
I've been a member of Linked In for almost two years now. I dutifully entered my credentials and kept them up to date. The only other interaction I've had with the service since then has been a continual stream of link requests. I'm selective about who I approve, limiting it to people I've only met in real life. And the net benefit of this selectivity? As far as I can tell, zilch. Nada. Nothing. I did get a cold call from a headhunter once based on my Linked In profile, but I don't consider that a benefit.
Has this service ever been useful to anyone? I'm telling you, Linked In is the digital equivalent of a chain letter. If you really want to contact a friend of a friend (of a friend), just pick up the phone or send an email. If the only way you can reach someone is through this nutty online social pyramid scheme, you don't deserve to be taken seriously. And I can guarantee that you won't be.
Consider carefully: who really benefits from your participation in Linked In? I'll tell you who benefits: Linked In.
If you can't immediately point to a few direct benefits you personally get from participating in Linked In, then why do it? Why build Linked In's marketing database with your valuable time and information?
From this point on, I'm opting out of linked in. Like Russell Beattie, I've found that there really is no there there. If you're a member of Linked In and you're not seeing direct personal benefits, I urge you to close your Linked In account as well. It's high time we put an end to this glorified chain letter of a service.