What Font Is - Find any font from any image (commercial or free)
Google Fonts - Making the web more beautiful, fast, and open through great typography
AMP Font Viewer - Jump to Download - Download.
Font Squirrel - Font Squirrel scours the internet in search of FREE, highest-quality, designer-friendly, commercial-use fonts and presents them for easy downloading. We don't have the most, but we do have the best.
Font Viewer - Font Viewer is an application which does exactly that - it views fonts!
Dafont - Archive of freely downloadable fonts. Browse by alphabetical listing, by style, by author or by popularity.