FontForge - Free (libre) font editor for Windows, Mac OS X and GNU+Linux
Font Awesome - Font Awesome makes it easy to add vector icons and social logos to your website. And version 5 is redesigned and built from the ground up!
BirdFont - Birdfont is a free font editor which lets you create vector graphics and export TTF, OTF, EOT and...
The Noun Project - Creating, Sharing and Celebrating the World's Visual Language
Glyphs - Make everything from dingbat webfonts to full-fledged text typefaces in the most Mac-like font...
Nucleo - Commercial vector icons and accompanying apps to manage and customize them.