I create my own. I search google for a subject, e.g. flame icon or fan icon. I then open the icon in Pixelmator and resize it and colorize it to suit my needs. Examples attached.
Any time I am industrious enough to add an icon and function to my Control Pages: 1: Internet search “myFunction + transparent png” 2: Download image 3: Use Photoshop (or Gnome, or whatever) to size it and to change the color palatte to what i use 4. Save new image to appropriate Indigo Web Server folder 5. Make new Control Page