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.
Google Fonts - Making the web more beautiful, fast, and open through great typography
Fonts.com - Fonts.com provides the biggest and best selection of high quality desktop and web fonts. Try, buy and download classics like Helvetica, Univers, Frutiger, Trade Gothic and Avenir along with popular new fonts like Soho and Neo. Find your type!
Open Font Library - The mission of the Open Font Library is to promote your freedoms as it relates to the use of type.
FontsAdda.com - Collection of 15,000+ free downloadable fonts for Windows and Macintosh.
Brick - Brick is an open-source webfont service that serves fonts in their original form for high quality rendering across all browsers.