Do you give your students timed tasks?  Do you use a kitchen timer, sand hourglass, stopwatch, or the classroom clock to mark the time?  Last year a colleague of mine turned me on to www.online-stopwatch.com.  The students are actually able to watch the countdown as it happens on the SMART Board™ and better pace themselves.  Teachers can choose from several versions including a digital clock, analog clock, egg timer, bomb, or split lap timer.  I use this site for giving math fact timed tests or oral reading fluency timed assessments.  It is also useful for counting down to the end of group work or setting time limits for transitions between tasks.