Chile de Arbole
These chillies are about 7.5 cm (3.5") inches long, very hot and firey and most often found dried. They have a fruity, smokey nose. Snap off the stem and crush two or three of these to add some heat to any spicy dish. They are often used to spice dips, oils and vinegars.
I obtained mine from the Cool Chile Co., when I last visited the excellent Chilli Fiesta, held every year at West Dean Gardens in Sussex.