A dynamic checklist that re-orders things based on whether you NEED them or whether you HAVE them.
So anything ticked, lives under HAVE (or DON'T NEED). Once you untick it, it moves to NEED.
Ideally when you open it, the things you NEED are at the top (or most obvious), and the things you HAVE or DON'T NEED live below or in a different tab.
Microsoft ToDo does this really well!