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
Font Viewer - Font Viewer is an application which does exactly that - it views fonts!
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.
AMP Font Viewer - Jump to Download - Download.
Open Font Library - The mission of the Open Font Library is to promote your freedoms as it relates to the use of type.