My students see me use it every week: the scale sheet comes out, my phone goes on the stand, and the metronome app opens and starts ticking. But, the musical usefulness of your smart phone isn’t limited to just one app. Below, I’ve listed come common tools that you can find for your iPhone or iPod touch. The key word I went with is “free,” so although there are others, I’ve tried to pick ones that don’t cost anything. Droid users - developers often write apps for both platforms (Angry Birds, anyone?), so take a look in the Android Market.
With as many free metronomes as are out there, you really don't need to buy one unless you want a smart phone version of Dr. Beat! In lessons, I use the Silver Dial Metronome. When you first open it after install, there are some features that I found distracting and chose to disable. Go into settings, and you can turn off "flash", "pendulum", and adjust the sound. With those settings changed, I found this to be my favorite metronome currently in the app store. Another one I saw is put out by Steinway. It's a very nice, straightforward metronome that allows you to pick a time signature, it has an optional flash, and a scroll wheel to pick your tempo. There is also a Ludwig edition, which has a couple more options for looks, but works the same way. I found them both to be very user-friendly.
Honestly, you're not going to find a free app that's very useful. The ones I saw were basic at best. Rather than spending the money on one, just open your browser and go to www.woodwind.org. There, you will find extensive fingering charts for flute, clarinet, saxophone, and even oboe and bassoon. It's free, accessible whenever you have a data or wi-fi connection, and is tested and reliable information.
There are only a few free tuners, but I did like one. It's called n-Track Tuner. It is an actual chromatic tuner, and although the app doesn't show it quite as simply as a handheld tuner, it does a good job of hearing pitch and showing the degree to which you are off. I put it up against my handheld tuner and it was pretty close. You can also choose a pitch for it to play. The runners-up were much less stable and they just didn't perform as well.
I didn't find any free apps that looked helpful. However, there was a good app made by a USC piano professor called Music Theory Pro for only $.99 that is a very nice study tool. It offers practice in note naming, intervals, chords, key signatures, and ear training. It does not teach, but is set up like a quiz game - you answer questions and it gives you a score. There is a timer that you can use if you want to add speed to accuracy. It covers content from what we learn in our lessons to a first-year music theory class. The only thing I didn't like about it was that you must answer the note naming component using a piano keyboard instead of giving the actual name, but for its purpose, I totally get why they went this route. With all that it does, this piece of software is a bargain, and is useful to students studying any instrument.