Today's tool is very simple and very useful. It was first pointed out to me by Ben Rimes over at The Tech Savvy Educator. It is Online-Stopwatch.com. Basically it's a stopwatch or a count down timer. I find online stopwatch very useful when trying to keep either myself or my students on task.
When we break up into groups to do a lab or a problems solving activity many students lack a sense or urgency. All I need to do to get them really moving is start up the countdown timer and turn my laptop so it is viewable by the class. Anyway, you should give it a look.