Well, I am a geek, not a designer, so my favorites The Visual Display of Quantitative Information by E. Tufte. Also Homepage Usability by Jakob Nielsen.
And going way, way back to my first experience of typography, the Letraset Rub-Down Type* Catalog. I used to wheedle the art store in town until they'd give me a catalog, then spend hours upon hours with tracing paper making words and alphabets in different fonts.
BV: Does that date me, or what? I say in my defence, I was 12 years old at the time.
* Oh dear, you're actually reading the footnote, aren't you? Which means you were probably born after 1980
This is, unfortunately, another "before there were computers" story. Letraset produced alphabetic sheets of characters, each sheet in one of many different fonts (plain and fancy). They consisted of a translucent carrier sheet, and individual letters in a rubbery vinyl film. You carefully positioned the sheet over your paper, and rubbed the sheet to transfer the letter onto the paper, where it stuck. You the repeated this, letter by letter, until you had formed the word, title or sign that you wanted to create. If you rubbed a letter down off-centre or crooked, you could scrape it off and try another one. This was type fonts for the masses, circa 1970. In the late 80's Letraset discontinued the rubdown sheets, and released a series of Postscript typefont libraries. They also took a run at producing image editing (Image Studio) font manipulation (LetraStudio) and page layout software (Ready, Set, Go), in competition with Adobe, Aldus and the fledgling Quark. The Letraset suite in its day was quite advanced, and sold as a bundle like Adobe CS is today. They gave up after a couple of years. Still have my dealer demo copies around here somewhere, just don't have a System 6.0 machine set up to run them on.