eXtended Account Management System (XAMS) allows Administration of Unix, Web, FTP, DNS, and email accounts to manage a provider's typical userbase. Especially focusing on email account management, it enables you to easily create accounts, set aliases, and delegate domain administration to 2nd party resellers or customers. It uses PHP with MySQL or PostgreSQL as a backend, and is therefore able to manage tons of email accounts independently from your Unix/Linux accounts. Exim for SMTP and Courier for POP/IMAP are fully supported, but postfix, Cyrus, and qmail can be used too.
Japt-Proxy is a fast and reliable caching proxy for Debian's APT system. It is intended for environments where several Debian systems have to be kept up-to-date and downloading the same files over and over again from the Debian mirrors is undesirable. Even with high volume internet connections, it can dramatically reduce the time required to install or update Debian on many machines.