One of the things I maintain at work is a self-installing Linux distribution.
When I started in 2002, we were purchasing KickStart installed Red Hat 7.x machines from a local company. With Progeny's AutoInstall, I managed to get a CD that would automatically install Debian Woody, but not in a very nice fashion.
Ubuntu came out, was more up to date than Woody (I think my Commodore 64 was more up to date than Woody for a moment there), and so I changed to it after the second release. Hoary introducted some support for KickStart installations, but I found that much more power could be gained with the new debian-installer that was coming for Sarge. A guide to remastering your Ubuntu CD ensued.
Two releases later, I updated all the machines to Ubuntu Dapper, and tidied up the installer a whole heap. Today, under the chargeable heading of "documenting my self-installing Linux distribution in case I get hit by a bus", I have given the Ubuntu Install CD Customization page a complete overhaul. Read it - it's grand.