The colors that this program creates are pretty cool, but sometimes several icons will turn out grey, because they use multiple vibrant colors which all average out to be grey.
I'd suggest adding in some additional logic that checks to see if the average color is dull, and if so, attempts to find a more vibrant color by seeing which color (or range of colors) appears most often.
Icons that look great: Opera, VMware, Pidgin, OpenOffice
Icons that just turn out grey: Google Chrome, Mozilla Firefox
Icons that I don't think you could do anything about: Windows Command Prompt, and other icons with no color in them at all.