• Copy across _add-ons/all_the_vars to your Statamic installation.
• Throw an {{ all_the_vars }} tag anywhere in your template to see everything that's available to you.

It'll look like this:

By default, variables starting with underscores won't be shown. If you want to see absolutely all the variables, which includes them, add remove_underscored="no" to the tag.

Google Webfonts is used because I dislike boring fonts. If this is an issue, add websafe_font="yes".