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!
Typography - Typography design and cloud hosted webfonts.
Flaticon - A database of free vector icons.
Fontello - Tool to build custom fonts with icons.
Google Fonts - Making the web more beautiful, fast, and open through great typography
Line Awesome - Same icons as Font Awesome, but in a modern outline style.