Ear Trainer

As the name would indicate, Ear Trainer is designed to train people's ears. Specifically, for intervals and harmony. There is a panel for each, as well as a mini-keyboard. Each panel will play a sound (interval or harmony) and you answer. It keeps score for that session, but the score isn't important, it's a tool to help you recognize the weaknesses in your ear, and learn what to work on.

The keyboard is also fun, it is small but it uses the computer keyboard layout pretty well, and is the only one I've seen to use the space bar as the damper pedal. It's also the only one I've seen where the keys actually move!

Ear Trainer is available on the Mac App Store. Search for “Phil’s Ear Trainer”

Noli n Nali Barcode Generator

Not a commercial app, and no longer useful since the company went bankrupt, but I still love this one. It generated PostScript™ barcodes which I put on the labels I designed. I learned PostScript™ long ago, when I was part of a team working on PS & PCL integration. Barcodes (well, the current ones, anyway) are fairly simple as they are just vertical lines with different strokes. Once the PS was written to a file, it was a simple matter to import it into Illustrator.

PostScript™ turns out to be the basis for html 5 canvas drawing, so it's still a very useful thing to know.

Stopwatch

Pretty simple widget. Acts as a stopwatch, has 5 lap times.

Stopwatch is available here.