Drag the bookmarklet above onto your bookmarks bar,
then click it when previewing a font!
You can install Typekit Tweaker for Google Chrome to have the toolbar automatically loaded on Typekit.
I normally want to preview a typeface using styles similar to those I'm using on the actual website I'm building.
I got tired of using Web Inspector to modify Typekit's settings. I got tired of inserting dummy text, too. This bookmarklet solves both problems.
Please report problems to the issue tracker on GitHub.
The code is available on GitHub and I welcome enhancements and bug fixes. If you'd like to help but aren't sure what to work on, here are some ideas: