This one's just for fun - geeky fun. As you know, part of book design is having an eye for fonts. How do we learn about fonts? If you're of an academic mind, the best book on the subject, ever, is The Elements of Typographic Style by Robert Bringhurst. You can learn about the history of type, structural forms, shaping the page, and much, much more. Bringhurst writes with such passion that you find yourself deeply engaged with the rules of acronyms and ellipses, ligatures and page proportions.
No? OK, then, how about playing a goofy game online instead? Check out www.typeconnection.com, a wonderfully designed site that lets you think about type in a whole new way. It's set up like The Dating Game, the old TV show.
You pick your font and try to find a good connection for it. You need to choose a strategy for finding a good match - by (font) family, by (visual) similarities, or by dissimilarities, since "opposites attract", or by shared history and influences - perhaps the same period or font foundry.
Next comes the part where you might actually learn a thing or two. Like the dating game, you skim the bios of the fonts competing for a match. Pick one, and you go on a date. You can see how the two fonts pair up. Incidentally, you'll learn about ascenders and descenders, serifs and strokes and curls. Mostly you'll just enjoy this website's interactivity and the creative way they make fonts the subject of a game. Check it out!