I'm one of the two developers for
RaceTrace, which is an iPhone app that does lap timing as well as data analysis. I'd personally recommend that
. Check out the news page on our site for some examples of how you can use the app to pick up time.
I will point out, if you're going to use
any mobile app, you'll definitely want to invest in bluetooth GPS device. Mobile phone GPS data is crap when it comes to data analysis purposes. We recommend either the
BadElf Pro or
Dual XGPS devices. With mobile phone GPS data you'll get lap times that are "in the ballpark", but not much else.
Let me know if you have any questions.