Adafruit Raspberry Pi Educational Linux Distro
Adafruit's tweaked distribution for teaching electronics using the Raspberry Pi.
BerryTerminal is a minimal Linux distribution designed to turn the Raspberry Pi mini computer into a low-cost thin client. It allows users to login to a central Edubuntu or other LTSP server, and run applications on the central server.
Gentoo is a custom Gentoo overlay for use with the Rpi2.
Minibian is a minimal Raspbian image using the Kernel 4.1.7, fits on a 1GB SD card, with support for RPi B, RPi B+ and the new RPi 2B.
With Pi MusicBox, you can create a cheap (Sonos-like) standalone streaming music player for Spotify, Google Music, SoundCloud, Webradio, Podcasts and other music from the cloud.
PressPi is a turn key Raspberry Pi Wordpress server. PressPi allows you to have a fully configured WordPress server up and running in just minutes.
Raspbian is a free operating system based on Debian optimized for the Raspberry Pi hardware. An operating system is the set of basic programs and utilities that make your Raspberry Pi run. However, Raspbian provides more than a pure OS: it comes with over 35,000 packages, pre-compiled software bundled in a nice format for easy installation on your Raspberry Pi.
RaspEX is a full Linux Desktop system with LXDE (an extremely fast-performing and energy-saving desktop environment) and many other useful programs.
RetroPie bundles together more than 30 emulators of much-loved systems from the past 30 years - including Amigas, Ataris, the N64 and the Sega Mega Drive.
RiscOS is a fast and easily customised operating system for ARM devices.
ROKOS is a distribution to launch a Bitcoin node.