Thanks for all the feedback, I have a few queries.
Thanks.  Please be sure to test the new faces with the following Emacs
configurations:

  . GUI frames with dark background
  . GUI frames with light background
  . TTY frames with dark and light backgrounds and with:
    - 8 colors
    - 16 colors

Do you know if there's an easy way I can test the faces on 8/16 colour terminals?
  (proced-run-status-code, proced-executable. proced-memory-default)
  (proced-memory-mb, proced-pgrp): New faces.
Minor, but do you mean to add a closing paren at the end of each line?  I saw this format in the commit log:
  (proced-run-status-code, proced-executable. proced-memory-default,
  proced-memory-mb, proced-pgrp): New faces.

This should probably be specified as percentage of total memory.  Or maybe
there should be a separate defcustom for the percentage, and the condition
should use both.  Just a single absolute threshold seems to cover only some
reasons for highlighting processes with large memory footprint.

I was thinking highlighting based on percentage memory would be more suited to the "mem" process attribute (granted though this is not implemented).  Though in hindsight a global threshold may not make sense if you're connecting to remote systems with varying amounts of RAM.  Perhaps the two thresholds could mark a percentage, say 10% and 50% of total memory?

I haven't tried your patch, but I'm curious whether it works also for
proced buffers of remote systems.
Hi Michael, I did a quick check yesterday and it seemed to work as expected.

This should happen only for proced running on the local system.
Thanks, this should be fixed in the most recent patch.

I've attached a more up to date patch, with changes to faces (mainly adding better defaults for light backgrounds), and a NEWS entry.  Also attached are images showing the current colour schemes on light backgrounds and terminals.

Thanks, Laurence