Simple operating system based on Linux that uses "modules", and loads everything into RAM. Can be persistent too.
Ranked in these QuestionsQuestion Ranking
Pro Surprisingly customizable
Fluxbox window manager is especially slick looking all considered, and the options one gets with it's toolbar, app bar, and wallpaper are surprisingly complex for such a small distro.
Pro VERY small
Can be as small as about 9MB, and with even X, wireless modules, and more, it takes up only 72MB.
Pro Use of tcz packages stored on media outside of MyData
Con Can be somewhat slow to turn on
Once it is up and going it is unrivaled in speed, but it can be sluggish when it comes to turning on, restarting, or turning off.
Con Not visually appealing
The operating system is not very pretty.