MacApper: How To: Create Custom Icons for your Mac

http://macapper.com/2007/04/21/how-to-create-custom-icons-for-your-mac/
"Have you ever wanted a custom icon for a hard drive or folder? I have, and I found out that it is easy to do, even if you can’t make an icon from scratch. For example, I got tired of seeing the default white removable drive icon whenever I plugged in my CompactFlash reader. I decided to make a custom CompactFlash icon to use instead."
From Nick: Quick note, this process, I've had problems with icons that have hollow centers. The click area doesn't register right. For solid shapes, like the example, works great, and the icons come out just fine.