[ctbeiser]

I'd say "bunch of fonts that are widely used." Some designers have obscure favorites that they use regularly.

If you're really looking for a good grounding in HCI fundamentals, The Design of Everyday Things, The Humane Interface, and, oddly enough, the OS X Human Interface Guidelines are among the best. For type, try "The Elements of Typographic Style," and for a basic, general overview of some concepts you should understand, "The Universal Principles of Design" is, well, not bad.