Domain Technologie Control (DTC) is a Web-based control panel for hosting that can delegate the task of creating subdomains, email, and FTP accounts to users for the domain names they own. It has support for many programs, including bind 8 and 9, MySQL, Apache, PHP 4, qmail, Postfix, Courier, Dovecot, ProFTPD, Webalizer, and mod-log-sql. It can also generate backup scripts, calculation scripts, and config files using a single system UID/GID, and monitor all traffic accounting per user and per service. It is fully skinnable and translated into several languages.
Arb-Scan is a remote banner scanner written in bash and Perl. It supports 12 different services banner checks (daytime, ftpd, sshd, smtpd, domain, finger, httpd, pop2, pop3, nntp, imapd and snpp). It features IP file reading, logging, random IP scanning, ftp anonymous login checking and VRFY/EXPN smtp checking.
Microbrew Message Center is designed to be an immensely scalable mail platform supporting multiple users, multiple domains, and multiple mail servers. It is akin to iPlanet or post.office but is not as complex and uses open source software to perform mundane services such as Web and mail services.