It's been on my list of things that I will almost definitely never take the time to actually work on, but I wished what I had was (A) a browser extension or GNOME extension that incorporates an offline version of all the DuckDuckHack modules, and (B) the same thing in an open source mobile app. (This kind of thing could just as easily live in a command line app, though, and I'd be super happy if a project maintainer incorporated them into something like GNU Units.) I looked into it, especially for (B), but I realized that the DuckDuckHack code depends on Perl.