I take a lot of screen shots of the various device breakpoints for responsive design and it takes a while to prepare them. This tools allows me to get what I need quickly, and hopefully it can be helpful for showing your more visual clients what you mean by responsive design when a suite of products isn't at the ready.
The Typetester is an online application for comparison of the fonts for the screen. Its’ primary role is to make web designer’s life easier. As the new fonts are bundled into operating systems, the list of the common fonts will be updated.