Auricular acupuncture is acupuncture of the ear. Since the ear is a microcosm of the entire body (the entire body is represented in the ear), there is an entire group of acupuncturists that deal only with disease by treating the ear.
One common use case for auricular in modern medicine is for addictions. Auricular has been proven effective in the treatment of various types of addictions.
Auricular : Chinese Medicine Living