I was tasting some ginger beers for a story and noticed that a lot of them taste like dried pizza flakes in the finish -probably a sign that they added capsaicin or other pepper heat to the recipe.
So I've listed the ingredients from the labels here and will add more as time goes on. (Or feel free to add them yourself in the comments if you have something handy.)
Crabbies Original Alcoholic Ginger Beer - Malt beverage without ingredients listed except for natural flavors and caramel color.
Bruce Cost Ginger Ale - Carbonated water, sugar, fresh ginger, citric acid
Maine Root Spicy Ginger Brew - Carbonated water, cane juice, ginger, spices
Ginger People Ginger Beer - water, sugar, ginger juice, citric acid
Fever-Tree Premium Ginger Beer - Spring water, sugar, ginger root, natural flavor, ascorbic acid