A couple of wild tangents:

> I personally am annoyed that after decades of evolution, we still have lots
> of common situations where people are expected to depend on the output format
> of programs like ls, ps, and so on.

I was just thinking over the weekend how convenient it would be if ls could
accept a format string to allow customization of the output, much like ps does.
Sure, you can always take the time to craft an awk/sed/perl/whathaveyou script
to reduce the output appropriately, but that's annoying for one-off tasks.
Alas, I think ls has used up all 52 upper and lower-case letters for options.
;-)

> I have worked on commercial apps where it was important to us to continually
> watch:
>     1. X server connection
>     2. socket/tty port to other device
>     3. child processes
> We ended up faking it with select() and pid-specific non-blocking wait() 
> calls.

Rather than banging everything into a file model so that select() will work,
I'd just note that with a proper multithreading implementation (where
individual threads block without blocking the whole process) this kind of
"watch everything" task can get a lot easier.  (It may not seem so until
you've programmed with threads, though.)