As a wizard I used shift alot to force myself to stand still, but I will probably dual bind a few of these to extra buttons on my mouse.
One thing I only just noticed (thanks to your question) was that pressing the numbers on the numpad have your character 'say' something ingame, it appears each character can say different things for each key.
Perhaps these are used to direct the followers .. will have to try it out later.
numpad 1: Get over here. Just stay with me. Come along. Follow!
2: Take this. Here. You want this?
will have to finish this later ..