Back in the old days, before the 156 came out, all Alfa owners used to wave at each other. I remember getting my new 2.5 V6 S3 in '97 and on my first trip out, saw another 156 and we waved madly at each other. That was the last time I got a wave driving a "modern" Alfa.
I still get waved at in my partners MX5, I get a nod from other Range Rover P38 owners (probably in releif that someone else is just as insane to own one as they are) and always get a wave in our RCZ.
I usually got a cheery wave when driving my Abarth 500, barchetta and when the 500 first came out we all used to wave, but thats all gone now. Seems popularity breeds contempt sadly.