I never tire of the conceptual trick of applying the metaphor of a map onto something non-geographical.
Mapping It Out: An Alternative Atlas of Contemporary Cartographies
by Hans Ulrich Obrist rounds up a set of maps created by artists and thinkers that chart what is often hard to visualize. The editor labels them "alternative cartographies."
Disclosure: one of the entries is mine. Several years ago I began asking people to "draw the internet" on a sheet of paper, and my own map of the internet is included here. That's the kind of conceptual cartography this atlas contains. I think of this as experiments in mapping the intangible.