http://www.metronomeonline.com/

This is a link to a free online metronome.

How does it work i hear you say?

Step1 Look at the scale of numbers printed on the metronome. The numbers indicate beats per minute.
Step2 Set the metronome at 60 (60 beats per minute) and turn it on.
Step3 Set the speed to 120 beats per minute, twice as fast as 60.
Step4 Start out on a low number, then gradually go higher.
Step5 Repeat the beat of the metronome on your instrument; for instance, if you are playing the piano, hit a key on each beat.
Step6 Read your music, paying attention to the tempo mark at the top of the page. For instance, if it says M.M.=100 (M.M. stands for Maelzel's Metronome), play the piece at a speed of 100 beats a minute. Set your metronome accordingly.
Step7 Play your music following the pulse of the metronome.
Step8 Turn off the metronome after you've developed a feel for the right tempo, and play the piece with the pulse in your memory.
Step9 Try this practice with a variety of music at different speeds. You will eventually be able to memorize the right tempo for every piece you play.

Here is a scale for you to try on the metronome