Serj asked me in a mail if I could list some books about graphic design theory. The amount of books on the market is astounding these days and I understand that surfing through the internet, with its wast resources, tutorials and inspirational site, its good to have the foundation to build on. Most of the theoretical stuff is normally taught in design schools and most of the books I will recommend are used in this context.
Many are not fancy or new, but the principles of graphic design still apply (just think about the bible printed by Gutenberg, is still considered one of the best justified text layout on the world). So lets get to the list - just a last word, I only recommend books I own or have read, so this list its genuine.