Came across this website today. It allows you to customize and build a Linux install disc with your choice of applications, desktop background and various other settings. Your customized Linux install disc is based on NimbleX (which is based on Slackware). The process is somewhat limited in what options you can choose, but it is super fast at building your image once you are done customizing.

http://custom.nimblex.net/

Since I am talking about building your custom Linux distributions I will also mention a resource to truly build your own custom Linux distribution from source. This site is dedicated to producing guides that allow someone to gather software from around the Open Source world and create a Linux distribution package by package.

http://www.linuxfromscratch.org/