This is an interactive .html file that will allow you to search for a trait or a tech and get all of the leaders and civilization that have that trait/tech. It will tell you all of the traits, techs, unique units and unique building for each leader/civilization. If you choose "None" as one of the tech/trait options, it will just show you the leader or the civilization instead of both at once (this is to allow for easier searching if you like using the unrestricted leaders option).
I don't know the original author other than what was put in the original file (says Zhahz). I just updated it to include all of the new info, unique buildings and search just leaders or civs.
Civilization IV Leader Picker BtS 3.17 2016-10-05
Civilization IV Leader Picker BtS 3.17