Firaxis has just announced a Modding contest for Civilization IV! There are a total of four categories:

• Best In-Game Asset (art, including units, buildings and/or wonders)
• Best World-Builder Scenario (just a single .wbs file)
• Best Map Script (just a single .py file)
• Best Educational Mod (only educators and schools can submit entries for this one)

The contest runs from Dec 23, 2007 to February 18, 2008. (Read the official announcement.)

Take note that in order to mod Civilization IV, you will need to have some (okay, quite a bit more than ‘some’) knowledge of Python.