Bangs are a common term across DDG users, and can be shared references, personal shortcuts not so much. It's a bit like language as a common understanding rather than individual headspaces. In a sense, bangs are social.

How useful that is or isn't I don't know entirely, but bang-based search seems to be a distinctive class of activity, and gives rise to its own forms of communication and discovery. I've learned (and shared) new sites/services through bangs.