Laconic: make a feature almost exactly like spoiler tags (click the button to reveal spoilers) except they would be used anything (BZP appropriate of course) EXCEPT spoilers.
But... why would you need to do that? If you're posting all of that, surely you mean to share it. I don't see why you'd want to hide it.
I mean sometimes people post huge blocks of text for things like background info on media and lists. Sometimes it makes the whole thing look messy and unnecessarily huge. I see what you're getting out though but I only mean for things like links and lists that are very very long. It should be discouraged for being used in discussions though.