Over the last few months at work we've been digging into the WordPress Theme Customizer and thinking about using it as the basis for a SaaS web app. Building upon the basic controls for the theme customizer is one of the challenges we've been facing and the Google Font Picker Control is the first of (at least two) the controls that we developed to make the Theme Customizer even more awesome.
I've finally started setting up the Theme Customizer in WordPress for my clients. I ran into an issue where the Theme Customizer has certain defaults that not all themes use. It is pretty rare for my sites to include a tagline; for us at BR the brand's tagline is usually included in the logo so we don't need to restate it. It would be very confusing if your theme customizer has an editable tagline that doesn't appear anywhere on the site.