Gadget: Stay In Tune for iPhone and iPod Touch.

Pros: Low cost. Easy to read. Very versatile.

Cons: Drains battery. No pickup mic.

Notes: Among the pages of iPhone apps I have, this is the one I use during lessons and rehearsals. Under the simple and attractive interface, it is a very capable tuner/tone generator. Along with the chromatic option, it can tune three kinds of guitar, banjo, violin, cello, viola and ukulele. It generates both synthetic and the recorded sound of the instruments listed in the tuning options. It can tune from A=400 to A=480. You can use headphone plug to amplify the tones, but there is no easy way to connect a pickup microphone. So, this app works great in a quiet room, but doesn’t work well in a noisy environment (especially for acoustic guitar and ukulele). Another thing to remember is, while this app is running, iPhone does not go to sleep automatically. If you are not careful, you can run the battery down. However, at $3.99, this is the best tuner you can buy.