Most drinks can be ordered decaf. The only exceptions I can think of off the top of my head are some of the tea-based ones like chais and green tea lattes.
However, no decaffeination process is perfect, so a small amount of caffeine will remain. If you're really sensitive to caffeine, there are options like hot chocolate (if you can tolerate the caffeine in chocolate), steamed cider, creme frappuccinos, or a cup of steamed milk with some flavoring syrup added (try raspberry!). There are also some herbal teas you can order.