Concept+maps

The [|Opte Project's] 2003 map rendering of the Internet: http://bitcast-a.bitgravity.com/blyon/opte/maps/static/1069646562.LGL.2D.700x700.png

An Atlas of Conceptual Maps of Cyberspaces (such as Linux Kernel and the American radio spectrum) http://www.cybergeography.org/atlas/conceptual.html

These aren't so much examples of concept maps -- more of information systems (in particular, transportation systems).

Moscow Rapit Transit System: http://www.usabilist.de/seeking/ru/images/MoscowMetroMap.gif

Design student's process work for the re-design of the London Underground: http://www.oskarlin.com/2005/11/29/time-travel