Here are some different peppers with pictures:
http://www.foodsubs.com/Chiledry.html
I believe you are looking for the "arbol chile." Dried ones are generally used in Chinese cooking.
My local supermarket has them, but yours may not. I'd search for an asian market.
EDIT: They're sold at
http://www.sweetfreedomfarm.com/chileprods.html, among other websites.