Awesome
Web Font Picker (WFP)
A bookmarklet that helps preview Google Web Fonts live on any website.
Usage
Copy all the code in bookmarklet.js
and add it to your browser bookmarks. Opening the bookmark on a site will load the picker in the top right corner.
Known issues
For security, some sites block scripts from unapproved domains, so the picker will not work on those (Github is one of them).