I'm very interested in the issue of how to effectively represent evidence and arguments, and this looks promising: spacedebate.org "is an effort to expand the debate on the weaponization of space through a collaborative wiki-like tool for structured debate on a topic".
The site has a quick tour which explains it well.
"Each side of the debate is broken up into positions which are composed of arguments and their supporting arguments, in a structured argument tree".
"The project is part of a larger effort, nicknamed the "Open Debate Engine" [the site is here, but it hasn't been released yet], which hopes to create a hybrid wiki platform that will be conducive to handling larger policy debate topics."
There's some rationale for having the structured format and what's wrong with the existing methods for online debate, here.
I think that improving an argument is often quite subtle, and can't be done without major revision of its structure, rather than by making changes within -- or by adding to -- its existing structure... so I think this is an issue that any site like this will have to deal with.
Some more info, from the about page:
Spacedebate.org is an effort to expand the debate on the weaponization of space through a collaborative wiki-like tool for structured debate on a topic. The project is modeled after Wikipedia, but instead of focusing on developing an encyclopedia it invites users to help edit and expand an 'argument tree' that reflects the various positions in the debate over U.S. military space policy. Users can browse the argument tree or an extensive database of resources, including links to relevant news articles, authoritative quotes, and a comprehensive bibliography of sources.