Simple. A list per member of staff, with all the projects that you are interested in making sure they complete in it. Go over it in the weekly review and you can feel on top of what your teams are doing.
Its also a useful tool for staff meetings and one on one supervision meetings - and reminding you about projects you should be doing.
I see no need to micromanage staff members by tracking their next actions, or even getting them to share their with me, I trust my staff too much. And if they let me down, it was their responsibility.
Obviously this is different to where you are working alongside your team on a specific piece of work, when you might create waiting fors when they say they will do something.