MatrixCaseSwapper for Mac

From Matrix Software:

This little utility might not be at the top of your Quark 6 must-have features, but if you find yourself changing the case of selected text on a regular basis, you're probably wondering where the keyboard shortcut is. The answer - until now - is that there isn't one. Preferences allow you to choose which number key between 2 and 9 (0 and 1 are reserved by Quark) to use in combination with the Command key (otherwise known as the Apple key) to convert the selected text to upper or lower case. The text attributes stay the same, preserving fonts, weights, colors and any other attributes the selected text may have.