The Stack Icon Generator is a simple web app developed by Will Woodgate. Click here to learn more.
You can use Font Awesome, Foundation and Typicon icons. This gives you the choice of several hundred vector font icons to incorporate into your design. The icon background, border and colour is fully customisable too.
The icon is generated at 512px square (at 72 dpi) and downloads as a PNG image with transparency. From hereon-in, you can put the icon through an Automator Action to generate different sized and named versions of the icon for your stack. Or use any one of the many icon generator tools available to create an icon set. You may wish to use some graphics software to apply addtional embellishments, like borders, rounded corners or box shadows.