the software i used to create the semantic maps in masterclass is called "Visual Understanding Environment" (I know, I know) and you can download and learn about it here:
it runs on java and so should work on any platform (Appletm OSX liger or whatever, Winblows, you name it) and is free to use. of course my chops with VUE are pretty bare bones, but with a bit of effort you can make these things quite clean and readable. so far i've been just using it as a quick way to write down thoughts, so i apologize for the lack of readability.
i've added the map that we did on free improvisation and the one connecting drumming styles from last year to a dropbox, and you should all have an invite to join, so check it out. if you want to try your hand at contributing to the maps, please upload your updated versions to the same folder, i'm not sure if images are embedded in the .vue file, so tell me if you can't see the cheezy pics of the drummers.