I downloaded a Linux distribution today called Damn Small Linux.  At just over 48 megabytes, this Knoppix-based distribution fits on one of those little business card-sized CDs.  It’s designed to boot from CD and operate without touching a hard drive, using a RAM disk instead.  It’s also possible to modify the distribution slightly to fit it on a USB memory stick.  With a 128 MB USB memory stick, you could carry your OS and a good bit of your work around in your pocket, and use it to boot almost any computer.  Carry the OS and the data, and borrow a machine wherever you are.  Now that is portability.

The other (or perhaps the primary) use of Damn Small Linux is as a diagnostic or troubleshooting tool.  With it, you can boot a crashed system, mount the hard drive volume, and explore to find out why the system isn’t working.  I burned a CD and added it to my little toolbox.  I know this one will come in handy.