Scalzi asks, What's your favorite obscure soda flavor? I'm responding here.
A lot of votes for ginger beer. I like ginger beer, and it's not something you see often in the average 7-11, I guess, though it's not hard to find one brand or another.
Perhaps my favorite truly obscure one is a pineapple soda from Hawaii, which I used to be able to get at a local Hawaiian market, but the place closed, so no more.
Another truly obscure one I haven't seen since the place closed where I got it is Inca Cola, which I once tried at a long-gone Peruvian restaurant in San Jose. But, unlike with pineapple soda, I wasn't missing it. It tasted like bubble gum.
But the obscure soda I searched for the longest was Moxie. I first heard of it from Bored of the Rings, whose authors were from Harvard, where Moxie has been heard of. But I didn't know even that much when I first went looking. Many of the characters in Bored of the Rings have food names, and the two young boggies are Pepsi and Moxie. At Mythcon once in the 80s we held a Bored of the Rings food party. We had Fritos and Arrowroot biscuits and Pepsi and I think some Spam and some other things (no Benzedrine, though - come on), and we wanted some Moxie but had never seen it and had no idea how to get any.
It wasn't until years later that I finally found Moxie, at the general store in Plymouth, Vermont, a tiny village now given over to the fact that Calvin Coolidge was born there. On telling this story, I have more than once been informed heatedly that Moxie is objectively vile and evil of taste. I didn't find it at all bad, and though I wasn't rushing back to get some more I have had it again since. The soda I find vile is Dr. Pepper, which lots of people like.