Here is the link to the Diplomacy rule change proposed by Rich Berlew (of OotS).

http://www.giantitp.com/forums/showthread.php?t=172910

I like it.  It's not a "make people like you", it's a "get people to do things with/for you"

Summary:

DC = 10 + 1/2 highest level + highest WIS mod of the group you want o persude

Circumstance modifiers to roll:

-10 to -5: Enemy or hostile

-5 to 0: Negative neutral

0 to +5: Positive neutral

+5 to +10: Friend or Ally

+10 to +5: High Benefit to the other party

+5 to 0: Moderate Benefit to other party

0 to -5: Moderate Risk to other party

-5 to -10: Huge risk to other party.

That seems rather easy. to work with.

hmm the only thing i would change with that would be the highest (level+wis mod) person. If there was the king (20th level, +2 wis mod) and his high priest (15th level, +5 wis mod), you wouldnt take 20+5 (king level, priest wis), it would be the better of 20+2 (king's bonus) or 15+5 (priest's bonus).