Just found a nice trick on TUAW on how to make the OS X Activity Monitor show graphs in place of its app icon.
I just needed to create an .iso file from a DVD and Disk Utility was no help. 🙁 So I turned to the internet and found my answer on SuperUser. 🙂
hdiutil makehybrid -iso -joliet -o Image.iso /input_path
There are other variants described on the linked page.