Derived from the fantastic boilerplate at https://github.com/khromov/wp-better-starter-widget
I created this really tiny plugin so that my children's grandparents can load the site and see how long ago their grandchildren were born (down the the day). I didn't publish this on the WordPress.org network since I don't think it is a plugin that has a lot of long-term value. But I'm storing it on GitHub in case somebody else wants to find inspiration from it.