Perljobs.Ru uses Perl
The whole backend part (deployment and other scripts, business logic, web interface) is written in Perl.
ΠΠ΅ΡΡ Π±ΡΠΊΠ΅Π½Π΄ (ΡΠΊΡΠΈΠΏΡΡ Π΄Π΅ΠΏΠ»ΠΎΡ ΠΈ ΠΏΡΠΎΡΠΈΠ΅, Π±ΠΈΠ·Π½Π΅Ρ-Π»ΠΎΠ³ΠΈΠΊΠ°, Π²Π΅Π±-ΠΈΠ½ΡΠ΅ΡΡΠ΅ΠΉΡ) Π½Π°ΠΏΠΈΡΠ°Π½ Π½Π° Perl.
papaver uses C
been programming in c for over a decade, since learning it in college. still use it for various low level projects. used it recently to develop an embedded application for a custom board.
jagalbraith uses Perl
I use Perl to rip through log files and compare them to some signature files I have created. When I get a match, it adds the bad guy to the list of shame in MySQL.
micro systems uses C
The core of the arcapos applications is written in C, so are most of the Lua modules (bindings to various hardware or protocols).
Sqreen uses C
The Sqreen PHP agent is both a PHP extension, built in C, and a daemon built in Python.