So far my favorite is the one that Gandolf made so that ALL of the nations could play in one big game. Like the Perpetuality, and the Evermore game that is coming up.
CBM (makes multiplayer a lot more even)
Worthy Heroes (makes the vanilla nations a lot more interesting)
Skaven (the best of the mod nations i have tried)
I think community ratings would be cool. Back when I was playing NWN and NWN2 (http://nwvault.ign.com/) I'd always try the ones that sounded coolest, but I usually played the highly rated mods much more.
Unfortunately this falls into the same realm as Idea: cannot implement, since I have no coding skills.