Earlier quoted context omitted.
The bang commands alone are DDG's killer feature for me, and it's why DDG is set as my homepage and default search engine (and probably still would be even if I did have to !g every non-site-specific query).
Had no idea about these DDG bang features, although admittedly I've barely used DDG. Usually use startpage if I'm not using Google. I imagine to there also might be a chrome extension that does a similar thing to the DDG bang features, or are these just DDG-only search indexes?
Try searching for “!w search engine”: DDG sends you straight to Wikipedia, which sends you directly to the relevant article. (Search “!bang” for more info about bangs.) When DuckDuckGo is your default search engine you can do this straight from your browser's address bar or OS's search field. It's very nice.
(I have no affiliation with DuckDuckGo; I just really like this feature.)