This is the Tiger version of a previously submitted hint. Basically, it allows Disk Utility to create disk images in many additional formats. Some are pre-OS X formats, and some others are new to Tiger. Plus, there is a strange (at least for me) ".ipodimage" format available.
To activate the hidden formats, just open the Terminal and enter this command (make sure Disk Utility is not running):
defaults write com.apple.DiskUtility advanced-image-options 1
Now launch Disk Utility and try to create a disk image from folder, or convert an existing image (the advanced options are not available for new blank images). In the Save dialog (after choosing a folder), pop up the "Image format" menu and see the additional formats listed. To know more about various formats, try to consult the man page for hdiutil (man hdiutil in the Terminal). Anyone know something more about the iPod image format?
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050601181738987