I use this, no idea how complete it is though.
http://joz3d.net/html/q3console.html

for cpm/cnq3/whatever-mod-or-executable-floats-your-boat commands I check the docs and the changelogs.

Edit: Just looked at that website, apparently it wasn't updated after 1.30, so if .31 or .32 added or changed any commands or variables, that list doesn't include them.