It is getting to the point that the iPhone is an essential studio tool. I just saw this amazing $3.99 app that will tune any instrument by just holding your iPhone up to the source. How well does it work? I just tried a Banjo, Ukelele, Melodica, and Acoustic Guitar with great results! If you have any odd instruments around and want to practice your pitch or tune them easier, I can’t reccommend this App more highly. It even shows you a graph of where the fundamental falls on each instrument. Too cool!