There was recently a discussion on the Amber Mailing List which dissolved into a Flame War, triggered by some musings about the possibility of adding a Social Stat to Amber as a house rule.
If I recall properly, it arose from a common problem; what does one do with Flora's points? None of the stats and powers quite seem to build a Flora that matches Zelazny's character, the Flora in the ADRPG book, or Flora as generally played.
The idea then was that if there were a stat to represent social abilities (I believe a reference was made to the Storyteller system as well), then Flora could be done up believably with a point value near that of the other elders.
I'll leave off the stuff that the Flame War circled around, and get to what I think is interesting, which is the benefit of throwing this up own my own journal.
What would I do with a "social" stat? I'd use it as a superior version of "Allies", for one; the higher the social stat rank, the more likely the character is to have an ally in the right place at the right time. Additionally, it affects reputation. If Flora uses her Socialise stat to attack Benedict, her player has to describe what she's doing (start a rumour that he was the one who swiped Random's favourite drums), and how (have it whispered in court, and in taverns). If Benedict has a high enough social stat, he can find out about the attack in time to do something about it (his spy network might be sensitive to this kind of thing; he might send soldiers to intimidate the people telling these rumours or seed dozens of conflicting rumours to defuse the whole thing). If Flora outranks Benedict, his defence fails. If she outranks him by a lot, he doesn't even realise its going on until it has become "common knowledge".
It would certainly shift the nature of character concepts if there was a stat like this in place.