I write Perl at Los Alamos National Laboratory for the Influenza Sequence Database. My group has a number of biological databases (HIV, HCV, Flu) and they all are written in Perl. woo hoo! In fact one of the databases might be looking for a student to code Perl.
I write in Perl only, of course I have to do other stuff for a web app like Javascript or SQL, but Perl is the language in these here parts.