For the local hockey club a small plugin was required, which provides an overview of the attendance of players. The reason was on the irregular attendance. To avoid an empty training with just a few players this plugin was established. Players can easily sign in by just entering their name. Later the attendance can be changed, but never deleted. This plugin provides no checking on the entries on purpose. Everyone can load the page and mark people as not attending.
After a while the Plugin developed and became a tool with rich functionality.
See an example at wordpress.dasweb.net