GPS Widget supports what3words locations.
If you don’t know what what3words is, have a look at the following video which explains it very well:
3 words to address the world from what3words on Vimeo.
Tim from what3words made a video showing how to enable what3words in the GPS Widget (thanks!):
what3words in GPS Widget from what3words on Vimeo.
So, if you are interested in what3words, GPS Widget is a great place to start: get it from Google Play