We play TORST, Trade Only Self Researched Techs.
We do this to limit the whoring and award inventing techs yourself.
For our diplogames wer have a lot of gentleman rules that aren't solid, like: don't capture the cap of another player, don't capture or raze big wonder cities. Have a background story for everything you do (no sudden invasions that aren't backed up by an in-game reason) etc. But that's typical diplogame style.