I still have CB's in both my pickup and my car.
My car is probably one of the few 4 wheelers around with a CB, but as much time as I spend on the road doing real estate inspections, for me a CB is handy. It's handy for checking road conditions, or if everyone on the Interstate starts to slow down it's nice to be able to pick up a mic and ask what's going on.
Don't know of any forums or chat sites for CB'ers. There's no where near the chatter there used to be. Now it's mostly just business.