And IMDB used to run on perl, I’m not sure whether it still does though.
I do get the impression though that most things that use perl were originally developed quite a few years ago. There don’t seem to be (too m)any new projects I hear about that are developed in perl.
DuckDuckGo does indeed run on Perl. Basically a scary not-modern-Perl non-opensource core surrounded by modern-Perl best-practices open-source Perl around it. Gabriel may eventually opensource the core stuff, some day. I get the feeling he was using Perl to play around with stuff so just kept using it.
Probably the company using Perl most obviously today is Booking.com. They are a known large black hole trying to suck up every Perl developer in existence. : P