Three books that I would recommend to any designer are Grid Systems in Graphic Design by Josef Muller-Brockman; Basic Typography: Design with Letters by Ruedi Ruegg; and Basic Law of Color Theory by Harald Kueppers. Since all designers should have a basic understanding of grids, typography, and colour theory, reading as much as you can about these things can only help.

Typographic Design: Form and Communication by Rob Carter, Ben Day, Philip Meggs is used widely for undergraduate classes today. There should be other book suggestions to suppliment this text and provide for more indepth exploration/understanding of typography. If colleges are fortunate enough to have a history of graphic design class, Meggs' History of Graphic Design is still standard. A book list is a great idea to help educators.

In addition to the good texts already shared or recommended (some perhaps less for class use than simply because they're interesting), I would add the four "Looking Closer: Critical Writings on Graphic Design" essay compliations and, for students, Lupton's new textbook, "Thinking With Type." She's also got a great companion website with some extra stuff for educators:

http://www.thinkingwithtype.com/

Here's one life-long design educator's brilliant articulation of his pedagogy, filled with tips and long-term perspective on shaping a design program that excels:

http://www.rit.edu/~rkelly/html/index2.html

Then there's always Loop, AIGA's "experiment in graphic design education":

http://loop.aiga.org/index.cfm

The Design Observer website often delivers interesting, ineractive stuff on design-related issues some students and educators might get something out of:

http://www.designobserver.com/

Cheers

Having only recently discovered your site (and many thanks for the effort and courage to MAINTAIN it) I'll keep my small growing number of posts brief:

Norman Potter, What is a Designer?
Robert Adam, Why People Photograph?
Roland Barthes, Image Music Text.
Paul Rand, Design, Form and Chaos.
Armin Hoffman, Graphic Design Manual.
Robert Irwin, Seeing is Forgetting the Name of the Thing One Sees.
Willi Kunz, Formation + Transformation | Micro + Macroaesthetics.
Karsten Harries, The Ethical Function of Architecture.
Ron Burnett, How Images Think.

My own bibliographic list snakes outwards from here, but in general, I'm less insterested in writing about graphic design itself, as in general, aside from people like Paul Rand, maybe Armin Hoffman, it tends to be poorly written or considered, or both. Its a nascent profession well accustomed to adding fragments of thought from other disciplines...from there, I find students, and colleagues, benefit from approaching the profession from the rich periphery, rather from the contentious core.