I love Disk Utility, however, it does not directly support the creation of ISO 9660 images. It can create CDR images or CD/DVD master images. Those can be renamed to .iso files and are supported by most software. But that's inconvenient to say the least.
Some searching revealed that you can create ISO images using the Terminal through hdiutil.
The Terminal command is:
hdiutil makehybrid -o ~/Desktop/Diskimage.iso ${diskName} -iso -joliet
However that still leaves things complicated. So I put this in Automator by adding the 'Run Shellscript' action.
echo -n `date "+%Y-%m-%d - %H:%M:%S ->"` >> ~/iso.log
echo "Starting ISO creation" >> ~/iso.log
diskName=$(drutil status | grep "Name:" | awk '{print $4}')
echo -n `date "+%Y-%m-%d - %H:%M:%S ->"` >> ~/iso.log
echo "Device: ${diskName}" >> ~/iso.log
echo -n `date "+%Y-%m-%d - %H:%M:%S ->"` >> ~/iso.log
echo `diskutil umountDisk ${diskName}` >> ~/iso.log
echo -n `date "+%Y-%m-%d - %H:%M:%S ->"` >> ~/iso.log
echo "Starting copy action."
echo `hdiutil makehybrid -o ~/Desktop/Diskimage.iso ${diskName} -iso -joliet` >> ~/iso.log
echo -n `date "+%Y-%m-%d - %H:%M:%S ->"` >> ~/iso.log
echo "Done" >> ~/iso.logI made this a Service in the Application menu (Snow Leopard only). Now I run the Service and the disk image appears on my desktop, when the CD/DVD ejects, it's done.
[crarko adds: The original command with hdiutil was mentioned previously in this hint. The use of Automator to create a Service is a handy addition to that.]

