Erlang, a language for concurrency, is a good choice for writing parallel programs to fully exploit current and future multicore CPUs.
Find out how much of the Mono 2.0 (and beyond) platform is available for Debian users who want up-to-date .NET compatibility.
Encrypt your files transparently in Linux with eCryptfs, an enterprise-class stacked cryptographic file system.
Build a system to securely talk to your Linux server via email using an email client, GnuPG, procmail, and PHP.
Use PHP to create a secure Internet file-sharing application that employs a database abstraction layer and separates HTML design from PHP programming.
Take a journey around the world of Ubuntu 7.10 without exiting from Debian. Along the way, you'll learn how to run multiple Linux-in-Linux instances for development and study.