We are just getting into the typography chapter in The Zen of CSS Design in my Writing for the Web class (btw: excellent text, but not for every teacher; the book assumes knowledge of CSS and XHTML which the teacher has to make up).

Since some students are thinking about using CSS text replacement methods, I wanted to provide them with some alternative fonts beyond those supplied by XP and MS Office. Vitaly Friedman's 25 Best Free Quality Fonts provides a list of 25 excellent fonts. Friedman not only provides links to their downloads, but also screenshots of sample type from each, making it easy for those who don't want to have to download fonts just to see them.

Many more free fonts are available at Font Reactor. Some good, some bad (just be prepared for an epileptic seizure thanks to one of the world's most annoying banner ads on that site).