"Ball", the Byzantine Askemos Language Layer, is an intrusion resistant and incorruptible, autonomous distributed operating system. It provides application programmers with continuations, messages, and rights management on top of a peer-to-peer network resisting byzantine failures of network nodes. The API significantly raises the level of abstraction in comparison with other operating systems: there are very few system calls, and these are expressed in XML. An alternative understanding of Askemos is that of an XML object database with stored procedures.
BasicLinux is a mini-Linux distribution designed specifically for old PCs. It provides a slim 2.2.26 kernel, a user-friendly shell and a good assortment of utilities. It includes a Web browser, a comm program, an email client, a telnet client, wget, DHCP, and dial-up PPP. It also includes a small footprint GUI, and is able to run remote X (via network) with as little as 4 MB RAM. BasicLinux is particularly suitable for old laptops: it comes with PCMCIA capability and includes the MagicPoint presentation program.
Coyote Linux is a mini distribution designed for setting up network utility services such as Internet connection sharing, firewalling, or wireless access points. The goal is to make it as quick and easy as possible to set up a Linux system with only a minimal amount of Linux knowledge.
eCos (Embedded Configurable OS) is an open source, configurable, portable, and royalty-free embedded Real Time Operating System. It is written in C++, provides all the usual OS things. You configure the OS so that the parts you don't need aren't loaded to the embedded system. eCos is released under a modified GPL that allows for its use in embedded systems without having to GPL the embedded application.