NexusFont - Choose and manage your fonts with Nexus Font.
Font Manager - Simple font management for GTK+ desktop environments
CufonFonts - The world's most comprehensive Webfonts supported free font archive. For designers and developers.
ClearType Tuner PowerToy - Windows XP and Vista users can use the online ClearType Tuner, or the ClearType PowerToy to...
fontconfig - Fontconfig is a library for configuring and customizing font access. Fontconfig can:
Gnome Font Viewer - A font viewer utility for GNOME