@Alexej K I looked at Nami.ng and would like to suggest a few more additions to it if you find them suitable. A few are big companies, others are small. I just happened to come across some interesting hacks while hunting for my own and certain others while looking at Wikipedia pages for CCTLDs.
mi.ne allmine.com Home Design Services
wapo.st washingtonpost.com
profa.ne profanemmo.com The game created by Insa.ne
bre.ad Yahoo
abc.xyz Used by Google for Alphabet
freig.ht freightos.com
red.green.blue bombfactory.com
slipstre.am Used by ansdor.com to promote a game called slipstream.
mechani.sm is used by mechanism.com which seems to be a startup so not sure.
microco.sm Microcosm is a modern forum platform
starfi.sh A web design company based in Philippines
thi.ng Open source building blocks for computational design. Est.2006
I remember way back I happened to register Hi.ht for no apparent reason. At that time freig.ht was available and I contemplated getting it, but sadly never did! And I was surprised to see bre.ad used by Yahoo! I love the hack red.green.blue as if you go to green.blue nothing opens, and only going to the subdomain red opens the page. I thought that was a nice touch! And I read a news article about Google acquiring abc.xyz to complete their alphabet.
Just like
@DomainHacks.com mentioned about Ma.tt, I would love using a domain hack for a personal website. I wish my real name was hack-able, but at least I got the .com for my firstname. However, I'd probably attempt to get the two-letter CCTLD domain for my nickname!
In a way, hacks are unique because while you can have xyz for whatever many extensions, you can only have one x.yz which makes logical sense. Leave aside cases like will.i.am and willi.am or where multiple extensions lead to the same word/phrase like physici.st and physic.ist
! Also, the popularity of hacks can be seen from the way a lot of pricing is driven by the organizations listing certain CCTLDs and almost all GenericTLDs in the primary market itself.
Cheers,
DomainGaze.com