Gentoo... building Linux
Gentoo Linux is the "techie's" distro. To install and manage this distribution requires time and effort to learn. Many old-timer Linux types recommend that new or semi-new Linux enthusiasts go through the Gentoo installation experience in order to gain knowledge of the real workings of Linux.
The Gentoo community is well known for its support. Gentoo also has an extensive and thorough handbook that walks new users through the installation process.
Read a first hand account of an initial Gentoo installation HERE. 
** UPDATE** Gentoo has released a new version (2006.0) that has a Live CD version. Included in this Live CD is a Gentoo Installer that allows for a GUI based installation, much like easier RPM based distros.
Look at the release notes and download it HERE!
Linux From Scratch
Another "do-it-yourself" Linux distribution is Linux from Scratch (LFS).
Linux From Scratch (LFS) is a project that provides you with step-by-step instructions for building your own customized Linux system entirely from source. You can read about this distribution and download the .ISO images from HERE.
Read a good review of LFS HERE
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Using the Linux Command Line
Great tutorials on using the command line in Linux can be found HERE!
A great list of BASH (Borne Again Shell) commands can be found HERE (600 + commands)

Need to Compile the Kernel or Software? Look at our links to great tutorials HERE!