http://susestudio.com/

it lets you create your custom linux distro in a much easier way than linux from scratch.
it's all web based, you chose your desktop manager, packages, apps, look and feel, ... and then you download your custom distro in the format you want (iso for installation or live cd, usb image to boot from a usb stick or a ready to use vmware image).

if you want you can even use your custom distro from SUSE's virtual servers before downloading it, to test it and make sure everything is the way you want, using it from your browser... (i think it's limited to 1 hour or something like that)
now this is something cool ! :D and speaks a lot about the modularity of linux