Just finished listening to Soda Kings pitch, I love the idea. I live in Canada, and while I was visiting family last week we were at a greasy spoons breakfast joint and they had Vernors.

They still make Ski soda, http://www.double-cola.com/product/ski/
The website has a find a retailer mapping application.

As a kid, I loved Tahiti Treat, and Wink (grapefruit soda). I also like pineapple flavored Crush, very localized to certain areas and hard to find.