Damn Small Linux (DSL) is, well, pretty damn small. And, for all it's skinniness it manages to provide a fully functional operating system complete with a graphical desktop, a good set of applications and a range of system tools. All of this is in a package that comes in at around 50MB, and which boots as a Live CD, USB, RAM disk, or even as preconfigured Vmware image. Hell, you can even run DSL embedded within Windows.
All of this makes DSL a great Linux distribution for those who want to travel ultra-light, (and let's face it, DSL is a lot lighter than most of the alternatives), and for those who want to breathe new life into elderly or under-specced hardware. However, the difficulty with most Live Linuxes is preserving data. This extends to just saving able to save your configuration settings. What happens when you want to make changes to the operating system or want to add or remove applications? The Office Damn Small Linux book goes a good way to answering all of these types of issue and more.