I learned probably around 80% of the shell commands I use through apropos. For example, if I'd been searching for the "pipe thingy" lbrandy's blog entry starts

I learned probably around 80% of the shell commands I use through apropos. For example, if I'd been searching for the "pipe thingy" lbrandy's blog entry starts out searching for, I might have typed "apropos pipe", and lo and behold, there it is at the bottom of the list: ... pipe(2) - create descriptor pair for interprocess communication pipe(8) - Postfix delivery to external command rotatelogs(8) - Piped logging program to rotate Apache logs tee(1) - pipe fitting "pipe fitting" isn't the most useful description, but given how few other things there are, it's not too many man pages to read, especially after culling out the things I already knew about back when I didn't yet know about tee(1).