Nifty Leopard Image Trick with the Dock

Here is my Leopard dock:

From left to right – these folders are my outreach, research, personal, publishing, rails, and teaching folders…
The trick is getting the image to show in the dock.
In each folder put an image named aaaa-something.gif so it sorts to the top.
Then tell the dock to view the folder sorted by name.
Your image wil be the icon!