It's good to sift through your old bookmarks every once in a while. With the advent of Web 2.0, it's even more imperative to do so. There's a huge tendency to bookmark anything & everything just 'cause you can.
And so, after sifting through some of my old del.icio.us bookmarks I've found a nice piece on Bash shell programming that's worth a mention. It's only a intro to shell programming, but "every master was once a beginner" ;-)
The article has links towards the bottom leading to more advanced material as well for those who need to know more advanced shell programming stuff.