Debate Graph
I recently found this lovely site with many similar goals to KenYersel: http://debategraph.org/
It also contains a great source of arguments on a wide variety of topics. So far, it also has a much higher quality of content than some of the mapping systems which try to get into a lot more detail.
Hoping to meet with the creators when I head down to london next (beginning of July), so if you are interested also, do get in touch.