It would be useful to have a collective page where people can record their CLI one liners that have been popping up all over *nix SE. Similar to commandlinefu.
I don't think so. Or rather, I think that's useful for sites like the one you mention (commandlinefu), but I don't think Stack Exchange is the right engine for a collective page of one-liners. How would you find one that solves a particular problem?
If one-liners are the real solution to a particular Unix/Linux problem, they're welcome in the particular question they belong to.
This sounds like it would be identical to commandlinefu, and commandlinefu is already set up to do it. Stack Exchange isn't good at big compendiums of information on a subject -- it's designed for finding a specific answer to a specific question. A question like "what cool one-liners do you know?" is too broad, doesn't have a single answer, isn't solving a particular problem, and is better off left on sites like commandlinefu that are designed for that sort of thing