FIPA - The Foundation for Intelligent Physical Agents is a non-profit organisation producing standards for the interoperation of heterogeneous software agents.
Linux Virtual Server - The Linux Virtual Server is a highly scalable and highly available server built on a cluster of real servers, with the load balancer running on the Linux operating system. The architecture of the server cluster is fully transparent to end users, and the users interact as if it were a single high-performance virtual server. It is under GPL licence.
Ncat - Makes it easy to pipe data between hosts. The syntax is similar to cat, but allows tcp streams to be specified in addition to regular files. (C) [GNU/Linux, Unix]
OpenMosix - OpenMosix is the free fork from MOSIX after this great project closed the user area tools to a closed-source licence. All OpenMosix is under GPL licence.
ZooLib - A library allowing to create native executable for GNU/Linux, Unix, Mac OS, BeOS and Windows with little or no need for platform-specific code. (C++)