From One Girl, One Laptop:
BTimer is a simple lap timing tool for auto racing. It is specifically designed for endurance racing; it was developed by One Girl One Laptop Productions to assist The B-Team, which competes in The 24 Hours of LeMons racing series. Other teams racing in the 24 Hours of LeMons may find this timer useful.
The app keeps track of all your drivers, lap times, and lap events. Each time your car crosses the timing line, you push one button and the app does the rest. The laps are recorded, and automatically uploaded in the background to a server of your choice so you can have real-time race results in your pit area.
The app is also stateless. So, for example, if the device loses power, you can reopen the app and race logging resumes with no loss of data.
We made this app for our own use, but thought other endurance racers might enjoy it as well, so we're offering up free of charge. Enjoy!