Actiu Informatica, Girona, Spain
We use Debian on various servers to provide common services to customers such as E-mail, Web Sites, Fileserving, Mailing lists, Remote desktops, Calendars and monitoring. We also use Debian internally for our organization's servers and for our customer's LAN servers. We chose Debian because it's APT based. Stable versions are very consistent, the project is community driven, and because of the project's policy about freedom and security.