iPhone Lap Timers?

[kthacher]

So I am off to the track tomorrow and was thinking of using my iPhone as a bit more of an advanced lap timer, than the built in one. Has anyone tried any of the tools out there including something called Harry's lap timer. I wonder if the built in iPhone GPS is good enough to be useful. http://web.me.com/hschlangmann/LapTi...page/Home.html

This is the day where I may also get some seat time in the new Porsche Turbo PDK as well. Maybe even an M3 too.

[Whirlinturbin]

I use the Dynolicious app, but not sure it has a lap time feature.

[harrison]

My freinds have a GPS app that they say is surprisingly accurate.As accurate as the Transponder.