[Techtalk] Guide to the command line

[Mary]

Someone in my lab is looking for what he calls "the web page to replace
Mary". What he seems to mean by this is a reasonably comprehensive guide
to the names of command line utilities. Anyone know of a page that could
fill this role?

What he seems to want:

 - a page of commands ordered by task somehow ("Commands to archive
   files: tar; commands to compress files: compress, gzip, bzip2;
   commands to check disk usage: df;")

What I'm pretty sure he doesn't want:

 - a simple introduction to the really basic command line file
   manipulation stuff (ls, mv, cp, rm)

 - man pages (they don't tell you the name of the command, they tell you
   how to use it when you know it)

 - a introduction to or tutorial on shell scripting

My Google searches kept turning up pages in the three "undesirable"
categories, and the LDP seems to only have "simple intro to the basics"
and "shell scripting" guides.

Has anyone got any good URLs that they recommend for someone who knows
their command line basics but has no way of finding out the range of
command line utilities that are available?

-Mary