What are the top 10 must play Civ 4 mods? I want to see if I have missed any? Please leave download links.

For me the basics are:

BUG: Beyond The Sword Unaltered Gameplay, an interface mod that makes all the information that is already available in the game infinitely more accessible. Very customizable, so you can choose exactly what information is displayed.

Rhye's and Fall of Civilization: civilizations are born throughout the game and can collapse with the new stability mechanic. Also adds new features such as a Historical Victory, based on the achievements or aspirations of real-life empires. Note that the version included with Beyond The Sword is not the final one. If you like the concept, there are dozens of modmods that expand the gameplay with new civilizations and settings.

Fall From Heaven II: a dark fantasy mod so deep and polished that it's basically a standalone game running in the Civ IV engine.

If you want to go really overboard, there's no one mod bigger for Civ IV than Caveman2Cosmos.

I'm really enjoying the Star Trek Mod myself.