Hey CW,
If you're going to have a system for serious use, it pays to learn Slackware. When people get started and don't know how to choose between Linux, *BSD, etc. it's nice to have some live CDs to see which types of Linux (and other *NIX) might be right for them. Slax live CD (Slackware-based) is a good example- the guy used to mention all over the website that Slax isn't intended to be installed but people started installing it anyway. It's a pretty nice distro and comes in all sorts of flavors to do just about anything out of the box without having to do much if any config. When you boot one of these live CDs you can play around with the command line, look at the init scripts, etc.
And then there are the users coming over from winbloze who don't want to deal with the relative complexity of Slackware. They often get started with plug and play distros like Ubuntu (Debian-based I think). Ubuntu does a pretty good job of setting up hardware without having to go asking questions everywhere.
DSL is a good example of a small Debian-based distro for people who don't like Debian
Debian is a real drag to set up- the base install can be really bloated if you don't know exactly how to do it. I got good advice on these forums after I screwed up the first couple of Debian installs (I hate the SYSV init and got bored to death with Debian) but DSL makes it easier to like Debian without too much tweakage.
People with more background probably start with base distros. I agree that Slackware is where it's at. But not everybody has the time or interest to set it up.
