Identifont

Here's a great site for all us book/print/typography geeks:

http://www.identifont.com/

Identifont has a lot of info about different fonts, and allows you to run a search on a font name to see a sample or similar fonts. But the most interesting part of the site to my mind is the "Identify a font" option, where you answer a series of questions about a font you've seen. It will try to tell you what the name of the font is. I've had mixed results using this to identify fonts I already know the names of, but it's still a neat tool.

Identifont also has information on downloading free fonts from other sites.