From Nat'l Geo News:
To get a sense of just how turbulent the 2005 hurricane season has been, consider this: Forecasters may soon exhaust their list of pre- selected names.
Each year 21 common names are reserved for tropical storms. There are just four left for 2005: Stan, Tammy, Vince, and Wilma. After that, they go Greek—as in letters of the Greek alphabet: Alpha, Beta, Gamma, and so on.