About.com Readers' Choice Winner for 2010: 1001 Free Fonts
Online since December 1998 there's way more than just 1001 fonts these days. Download free fonts for Windows and Macintosh. Organized alphabetically and by style you can also view a preview of each font in text of your choosing. Part of the appeal of this site is its simplicity, and of course the quantity of free fonts.
The other finalists: