Unix
Cool, but obscure X11 tools has a list of obscure Unix tools from the day back when XFree86 rules the world. Many of these tools are no longer included in the official repositories,so you might need to hunt them down and compile from source.
Cool, but obscure unix tools is a list of modern, updated Unix tools. Still wonderfully obscoure.
You can download the three legendary Unix posters in full quality from archive.org.
