Font style matcher
If you're using a web font, you're bound to see a flash of unstyled text (or FOUC), between the init...
Typography
A New Responsive Font Format for the Web | CSS-Tricks
Nick Sherman gave a fascinating talk at Ampersand earlier this month which was based on an article he wrote called Variable Fonts for Responsive Design. In
FontReach
FontReach scans the top million sites to show font usage across the web.
WhatFont Tool - The easiest way to inspect fonts in webpages « Chengyin Liu