SoL (Server optimized Linux) is a Linux distribution completely independent from other Linux distributions. It was built from the original source packages and is optimized for heavy-duty server work. It contains all common server applications, and features XML boot and script technology that makes it easy to configure and make the server work.
Yum (Yellow dog Updater, Modified) is an automatic updater and package installer/remover for RPM systems. It automatically computes dependencies and figures out what things should occur to install packages. It makes it easier to maintain groups of machines without having to manually update each one using rpm.
Grml is a live system (live CD) based on Debian. It includes a collection of GNU/Linux software especially for system administrators and users of texttools. It provides automatic hardware detection and its default shell is the zsh. You can use it e.g. as a rescue system, for analyzing systems/networks, or as a working environment. It is not necessary to install anything to a hard disk; you don't even need a hard disk to run it. Due to on-the-fly decompression, it includes more than 2 GB of software and documentation on the CD.
Virtual Appliances are nano-sized virtual machines for deploying instant infrastructure and applications. They are Ubuntu Server Edition 8.04 based and available for VMware, QEMU, KVM, Parallels, Xen, Virtual Iron, Virtural PC, and Virtual Server. Available Virtual Appliances are a LAMP Server, LAPP Server, Apache Tomcat Server, and Cacti Virtual Appliance. These are the smallest, most functional, and easiest to use Virtual Appliances available. They are certified for use on VMware and Parallels.
APT-RPM is a port of Debian's APT tools for RPM based distributions (Conectiva, Red Hat, SuSE, ALT-Linux, etc). APT is an advanced package management utility front-end which allows you to easily perform package installation, upgrading and removal. Dependencies are automatically handled, so if you try to install a package that needs others to be installed, it will download all needed packages and install them.