Gnome
Here is a website for an icon tool.
There is an applicatioin called Gnome that I had heard of for iconography.
https://developer.gnome.org/hig-book/3.5/icons-design.html.en
Gimp
A free application for graphics that you can download.
http://www.gimp.org/tutorials/Creating_Icons/
Icon Ideas 24x24
http://www.axialis.com/free/icons/pre010.png
Examples using colors
http://www.axialis.com/free/icons/pre001.jpg
