Awesome ubuntu respins (wow, this is what I have been looking for forever, its perfect) https://help.ubuntu.com/community/LiveCDCustomization
Nice ubuntu remaster, notice how they copy certain home folders to /etc/skel http://crunchbanglinux.org/forums/topic/2859/remastersys-guide-create-your-own-ubuntubased-distro/
http://en.wikipedia.org/wiki/List_of_remastering_software
remastersys (debian ubuntu) systemimager (any?) kickstart (Red Had/Fedora/Centos) remasterme (PCLinuxOS)
Mount an ISO, then chroot, then edit, then save ISO and burn http://blog.dipinkrishna.info/2009/07/customise-or-remaster-ubuntu-904-jaunty.html
Reconstructor is a web based customizer, with lots of options, apps, backgrouns, icons... Debian or Ubuntu https://build.reconstructor.org/
Tuxradar (how to spin many distros!) http://www.tuxradar.com/content/build-your-own-linux-distribution-easy-way
Nimblex (slax I believe, web based builder) http://custom.nimblex.net/
Suse Studio, probably the best web based builder http://susestudio.com/
Revisor (for fedora)
Instalinux (another web based)
Larch to respin Arch Linux
Of course Linux from scratch LFS