Scrolling over a long list of time zones is annoying. It should be enhanced somehow.

These solutions come to my mind:

1. Reducing of duplicates from combo box as described by greenforest in http://goo.gl/htEiJV However countries or regions observing DST have to be contained too.

2. Suggesting of time zones when typing (most likely in a dialog window).

3. Selecting of a time zone form a map.