Don't want to be a party pooper but not really!
The thing is Civ3 benefited from modding because it, well, wasn't very balanced strategically. Civ4 could use a few minor tweaks here and there, but overall I was rather impressed at what they achieved out of the box. Since I am about the biggest balance nazi I know this is quite high praise.
The biggest changes needed like the maths chop change and some of the civic upkeep issues have been done already.
Also, your timing is a little off with Warlords about to come out. Maybe if they break the game with the x-pack there will be more value in a 'Poly mod. However, since they used many of the same community crew for beta testing I'm reasonably confident they wont.