Concept maps are often useful for faculty as well as students.  The National Science Digital Library has quite a collection of concept maps.  For example, the NSDL Science Literacy Maps cover topics like stars, chemical reactions, and social decisions.  For details, go to:

There is a recent article in Science Scope written for middle schoolers.

“Teacher’s Toolkit: Linking proportionality across the science and mathematics curricula through science literacy maps ” Kerri Richardson, Catherine Matthews, Catherine Thompson. Science Scope. Washington: Nov 2008. Vol. 32, Iss. 3; p. 64 (7 pages)

There are also some sources for mapping the concepts within a discipline.  hyperphysics has been around for while, and it has now expanded to include concept maps for biology, chemistry, and mathematics.  I use them when I am not quite sure where a concept fits into the big picture.