As both a lawyer and a nerd I am always interested in the technology behind negotiation. So much so that I've even created custom Members templates to help me out during mediations. Recently I discovered an app for the iPhone and iPad, inDispute, that's engineered around making reasoned arguments. The idea is to help you script out arguments and counter-arguments, making it easier to get your point across (and hopefully take some of the emotion out of an argument). It's an interesting and app and one I never quite imagined existing but isn't that what the App Store keeps doing to us? Giving us apps we'd never imagined before.
Either way, inDispute is worth checking out before you make your next argument.