Linotype - Linotype: Fonts for Desktop, Web & More
Font Viewer - Font Viewer is an application which does exactly that - it views fonts!
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!
NexusFont - Choose and manage your fonts with Nexus Font.
Google Fonts - Making the web more beautiful, fast, and open through great typography
Font Manager - Simple font management for GTK+ desktop environments