It should come built in the iPhone!!!
This thing Blows' away Apple's built in Clock Timer app. By a mile! No competition.
I have a lot of things I like to time, like my washer and dryer when I go to the laundry fluff and fold. I also like to time some of the foods I cook, so this is perfect. I can time my turkey, the green bean casserole, then and when my company is supposed to arrive, all in one app. It's perfect. Makes me feel like I'm the producer of my own dinners! :) (I kind of am).
It even drops timers in my calendar and lets me email them to other people for their calendars. This app goes so far, I can't imagine needing any other timer. Like for when park my car at a meter and it runs out in one or two hours. Or those expensive parking lots that cost $20 per hour. Anyhow it's saved me about $100 already.