I haven't been able to open any of the pictos font files bundled with ST 2.2. Also the character codes aren't sequential so I can't create a quick script to show them all without copy and pasting every name from the _Class.scss file (about 420) and doing it by hand.
How are we supposed to know what icons are available?
We don't have a complete listing anywhere except for looking at the code. The /touch-2.2.0/resources/themes/stylesheets/sencha-touch/base/mixins/_Class.scss and scroll down to find the icon-character-for-name mixing, you will see the long if conditional. Here you can see all the supported names that are the values you should be able to use in the iconCls config.