I know for sure there's a whole bunch of console stuff I don't use. But now I know about console.group() and console.groupCollapsed(), which absolutely delight me; there's a non-trivial number of times in my life when I've console.log()ing something about absurd numbers of things on a given page. The above methods give me a handy way to tame that output so it's a shade more useful.
Today I Learned
...about console's group method