My first iPhone App recommendation:
micFrequency by Spectrum Bridge
Here is a handy little app for locking on available wireless frequencies in your area. Works on the iPhone and is available in the App store for $4.99.
The app uses the location services to pinpoint your location:
As you can see here, where my church is at is a wireless nightmare.
Clicking the info button on the top right side shows you the actual frequencies you can use:
This app has helped me out of several jams, especially when Super Bowl 2012 was in town.
Good luck Locking On!