From super teachers tools page we have this two great resources that could be really useful for your classes.
Classroom Timer
Sometimes you just need to quickly put up a timer on the board during testing or other timed events in the classroom. Here is a very unique timer for such cases.
Classroom Countdown
If you need your students to know how much time is left for testing, writing prompts, or any other timed event, this page will let you count down in style.
Use Classroom Countdown
