Go to Google Scholar and search on "argument maps" and "argument diagram", you'll get plenty of hits.
A decision matrix is a very simple tool that can give an overview of an argument. Points for and against each alternative have positive and negative values.
However, if those values themselves depend on other calculations, or are interdependent, the decision matrix provides no way to display that, so it is not a complete modelling language.
Not quite in the same class as the listed software. Useful, I've used them, but they get really complicated with more variables. If you look at what they've got, it doesn't exactly seem bayesian. They don't work of probability, but off of absolute truths. Debating each piece of minutia in a sort of tree structure. It could definitely be improved upon.
The IMPACT project, funded by the EU, is building a tool to make debates easier to keep track of, and presumably more rational. It look sort of like an AI, where all the dirty work and low level stuff is done by humans, but the actual result is determined by the structure of the machine. Certainly you could subvert it by placing incorrect standards of evidence on particular papers/arguments, but on the whole it looks interesting.
Sort of a wiki-decision framework.
What do you think about this type of project? Are there any existing argument modelling languages, like UML for arguments? Is this the best approach?