Hey guys,
I've just completed a seminar in Melbourne and a few of the guys who attended asked me about an app I use to time my FSP work. It's called Ultra Timer and it's awesome. I am not the developer of the app, and I can't remember if it's free or not, but it's a good tool to use.
It's fully customisable, including rest periods and is sound and visual based, so no headphones required unless the gym is noisy.
My 2c worth.
Enjoy.