Set Helper is a simple Java applet that I created 7 years ago(!) to facilitate the calculation of pitch-class sets. It is designed using an interface which resembles a calculator.
The buttons numbered from 0 to 11 represent pitch classes. Click on the buttons which correspond to numbers in the set. Once you have typed in 3 different numbers, the program will begin to display additional information on your set. You can type in a maximum of 9 different members for each set. Click on Reset to clear the display and start over.
Click here for the source code, if interested. But keep in mind that this was my first Java program ever :)