Google Fonts - Making the web more beautiful, fast, and open through great typography
Hack - A programming language for HHVM that interoperates seamlessly with PHP
Typewolf - Typewolf helps designers choose the perfect font combination for their next design project—features web fonts in the wild, font recommendations and learning resources.
Fontstand - Try fonts for free or rent them by the month for desktop use
FontJoy - Get smart font pairings in one click
Font Generator - Tons of font ideas in one click