timer to add the element of surprise.
But what about when you're doing dry fire practice? Standard shot timers won't pick up the click of the hammer falling on an empty chamber. The usual recommendation for timing your shots for dry fire is to set a par time on your timer, then try to beat the second beep when you complete the draw or "shot." I find that method cumbersome for determining your time exactly. That's where the SureFire Shot Timer for the iPhone comes in. The sensitivity setting on this app can be easily adjusted to pick up the clicks when doing dry fire.
After turning up the sensitivity, and selecting random start in the settings, the iPhone can be placed on a nearby chair, or used in a belt or arm case if you have one. I use this app frequently to test my time to draw from the holster and get the first shot when I'm doing my dry fire practice. If you so desire you can even email your times to yourself directly from the app. A word of warning, a high sensitivity setting can also cause the app the pick up the sound of the gun going back into a Kydex holster.
What about live fire you ask? I have had mixed results using the SureFire Timer at the range. The noise canceling microphone on the iPhone sometimes interferes. The latest update to the app is said have fixed previous issues, but frankly I've never tested it, preferring to use my standard timer in the range.
Update: Unfortunately, as I looked for a link to the app, I learned that the SureFire Shot Timer is currently not available in the iTunes store. That's too bad as I find the app very useful for dryfire. I have found references to it online as recently as August of this year, so it's removal must have been recent. Perhaps it's something to do with the release of the iPhone 5. That's disappointing as this is a useful tool. Let's hope the folks at SureFire will bring it back soon. There is an undated press release describing the app on their website.
Update, October 29, 2012: As of this update, the app is back in the iTunes store here.