I'm looking to install an extremely light-weight flavour of linux on a USB stick. It also needs to be basically only CLI. Has anyone ever looked for something like this? Ever found something good?
To be particularly minimal, you could roll your own. Fair warning: this is an endeavor of many hours, but you'll better appreciate what goes into getting your OS pieced together.
Linux From Scratch is a very actively maintained step-by-step guide on just that: http://www.linuxfromscratch.org/
MicroCore is a command-line only variant of Tiny Core Linux.
Ubuntu Server might be what you are looking for. Because servers are usually headless, the basic setup does not contain any GUI parts.