I've been using LinkedIn since its beta. It is a great professional tool. I also use Facebook, Xing and one other that I can't remember at the moment. I find LinkedIn to be the best at connecting to people I know and trust.
KathyWdrf I found you on LinkedIn and looked at your profile. I switched from Taxation to Software, but that was 20 years ago.
My policy is to not link with someone I don't personally know. I did link with 'Flip' which is how I came to join Xing/OpenBC during its beta even though I don't personally know 'Flip'.