What a great tool LinkedIn has become for me.
Like anything, you get out of it what you put into it. I've taken some time to dredge up the names of faces I've met throughout the 15 years I've been a technology professional, and have been elated to find so many of them on LinkedIn. Reconnecting and catching up with former colleagues has been quite a joy. I only wish that more of them were on the service; I hope I've not lost all contact with those individuals.
Interestingly, participating in the Q&A section of the site has allowed me to establish connections to individuals I'd have never otherwise met or known. In particular, I'm now connected to someone in the Netherlands, someone in China, and have made the acquaintance of an individual in India. I have been able to provide career advice to a young professional searching for his way, and have been fortunate to receive many letters of thanks from both the question's authors and those who have found the words helpful.
The best thing LinkedIn has done for me, however, has nothing to do with their service. Realizing what LinkedIn really does happened in stages. There was the "What is this, really?" stage, then the "Wow, this could be a great showcase for me" stage, followed soon afterwards by the "Who else is on here" stage. Not long after that, a tiny dose of panic set in - how many people that I've known would be happy and eager to accept my invitation to connect? Any bit of self-doubt you had growing up in a cliquey school system comes rushing back. Fortunately, over 100 individuals I've known (and have recently met) are now connections; but the lesson taught by a desire to grow your network has been learned; Treat *everyone* you meet as if you'd like them to happily accept your invitation to connect.