University of Economics in Poznan, Poland
The server room has four Debian servers. The servers run SMTP software (postfix / qmail), database software (mysql), DNS (bind9), HTTP (apache), FTP (proftpd), also things like: MUD game server and music streams. We are planning on setting up a laboratory for the students with Debian workstations.
We chose Debian mainly because of the ease of updates and installing new packages and because Debian has so much software to choose from and the lists are easily extensible.