This also works with any website wich supports search I think. Other good ones include "!hoogle", "!hn", "!yt", "!g", and the list goes on.
Worth pointing out: submitting bang ideas is very, very trivial, but the whole process may last months. Last time I've read about someone complaining about a long bang, I've submitted "!gw" as a shorter version of searching Gentoo's Wiki and it became a thing a couple of days ago. This is maybe fifth or sixth bang that I've submitted to them via https://duckduckgo.com/newbang.