Quickly fixing other people's messes.
That means when someone else's vital component has an issue, and you've never seen it before, you can parachute into the codebase, figure it out, brainstorm a fix on the whiteboard, code it, and get it working using whatever their dev stack is, and commit the fix by 4PM.
The corollary to this are people who "are waiting on an email back".
The most valuable skill in tech?