This is my library mapped by reading order -- which books lean on which.
Center vs. rim. The foundations sit in the middle: books a lot of others build on. Out at the rim are the books that build on others, the ones to get to later. The dashed rings are just a scale, with "balanced" halfway.
Arrows run from the book to read first to the one that builds on it. Solid means you really want it first; dashed means it's good background.
Hover a book and its links light up: amber coming in from what it builds on, blue going out to what builds on it.
Color is how I read it (hover the legend for what each one means). Filled means I've read it. Bigger dots have more links.
Click a book to pin it. The panel gives its reading path -- everything to read first, in order -- or flip it to see everything it leads to. The address bar then points right at that book if you want to share it. Esc or a click on empty space closes it.
Scroll to zoom, drag to pan, drag a book to move it around.