I'm from Chicago, when I moved to Tampa and asked for a "pop", I was looked at like I was an idiot. Now I use "soda" full-time.
Here in Tampa when you ask for an Iced Tea at a restaurant, the waiter/waitress follows up with; "Sweet or unsweet?". That threw me off the first time I heard it.
One of my cousins was sent off to France as a foreign-exchange student by
Penn State. He asked for water there (it may have been tea), and the server asked "With or without gas?". Gas meaning, bubbles I guess, like seltzer water.
Edit: The map shows that the Tampa area uses the term "Coke". I don't think thats right, people use that when referring to the brand, Coca-Cola.
Heh.