It's a bit late, but one of the early posts in this thread has outdated information.

Taiwan used to have an outgoing tax you had to pay just before going through immigration. This was eliminated about 2 years ago, and all taxes are now included in your ticket price.

Also would like to point out that this thread really should be talking about additional departure taxes. Nearly every airport, including US domestic airports have departure taxes, but most developed countries have the airline collect this as part of the total ticket price.

Some countries still collect departure tax manually as you leave. It is best to always ask ahead of time, as it is quite a hassle to end up at the airport trying to scrape up cash to pay an unexpected tax.