I prefer the "select a nearby city" method of selecting your timezone. The "GMT minus X" method is off by 1 hour for half the year. But if I select "America/Chicago", I know that I'll always get Central Time as defined by the current political tweaking. Those politicians seem to like to change when Daylight Saving Time starts a lot.

• Eastern: America/New_York
• Central: America/Chicago
• Mountain: America/Denver
• Pacific: America/Los_Angeles
• British Time: Europe/London
• Central Europe Time: Europe/Paris
• Eastern Europe Time: Europe/Athens