X-Mind is an open-source mind-mapping package. Mind maps are diagrams that illustrate relationships between ideas or things. They make a great way to show lineages, influences, etc.
Go out to the X-Mind Website and pick up their latest version. Play with it and post items that are interesting!
There will be more items come up in the future on interesting infographics packages.
I've been using Inspiration for a couple of decades now; it is not expensive, but free is cheaper. I'll take a look at X-Mind.