The Absence app lets you enter your planned holidays and at the same time keep track of when your colleagues will be absent.
Audit is an app that allows you to see what happened with other users' content. When did a document get published? When was that task completed? Where was the image deleted? This helps you to help people fix things if you by accident misclicked something.
Case manager is a management tool that allows for keeping track of the progress of tasks being fullfilled across multiple workspaces.