I think the thing that amazes me most are the connections you make with "odd" cars like my Rambler and Buicks. Where I had known a couple of "Buick nuts", then along came the net. OH MY GOD, I have people all over the world who own Buicks that I can chat with. My Rambler, I ask one time on the AMC forum for some radio knobs for my 1959 American and have them in my mail box a week later!
It is truly wild, never could I have dreamt of it when I was a kid trying to find parts for my Honda C110 50.