Custom Built Countdown Clock

This is a quick and easy job for somebody who knows what they are doing. I need a custom built count-down clock that is web-based. I will be posting this count-down clock to my blog. I would like it to be a count-down timer that flows continuously in the format of 30 seconds 15 seconds, 30 seconds, 15 seconds, 30 seconds, 15 seconds, and then can be replayed for 2 more cycles like this one. It needs to be very simple, visually appealing and set to music or a simple beat. I have examples of timers that I currently like such as: [login to view URL] I would eventually like to have several clocks made, so if this is up your ally, there is potential for more work. Thank you!