Here are some many ways to use a kitchen timer to help with discipline.

1) Use it to help kids get ready faster, play "beat the clock", set the timer and tell them they have to be ready before the timer goes off.  Great for getting ready for school & bedtime without all the nagging.

2) Use it to speed up clean up time.

3) Use it to help siblings or sharing during playdates.  Once it goes off then someone else gets to use it.  This is great for when the kids are too young to know what 5 minutes is.