Ubuntu Customization Kit is a tool that helps you to customize official Ubuntu Live CDs (including Kubuntu/Xubuntu and Edubuntu) to your needs. You can add any package to the live system, including language packs and applications.
Read about it at Freshmeat
Release focus: Major feature enhancements
Upgrading the kernel should now be possible. During the building process, you can chose to launch a package manager or a console for fine-grained customization. A check for CD size was added. Trapping signals to unmount filesystems in case of error were added. customize-cd-gui was renamed to uck-gui. Many bugs were fixed.