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.
If we had lots of people playing mods I would agree, but currently I think it's only a small number of players who actually use them.
We're on the 3rd MP mod game now and if we keep organising stuff like that people will get more of an idea about which are the best mods, or at least suit them best. I try to be pretty impartial, because I'm a modder myself, but by making CBM versions of only certain mods I guess I'm playing favourites.
This thread might do better in the main forum actually - I guess there are people there who play a mod or two (probably WH and CBM) but never really come in here.