One suggestion I have is that the graph view seems to clutter up pretty fast. Maybe have a slider that increases the length of the lines between the vertices. Also, a SVG export would be cool for visualizing related concepts.
The graph visualization / performance is definitely not ideal. I spent a ton of time trying to make d3 more performant and layout the graph more nicely, but ultimately I just had to cut my losses and go with what I had. I do think there is room for improvement and I'll look into your suggestion, which is something I didn't consider. SVG export is also a great idea!
Easter egg? I never have JS enabled on random websites.