MLDonkey is a multi-platform multi-network peer-to-peer client.
WideStudio is an Integrated Development Environment (IDE) for building window applications in C++, Ruby, Python an Perl for Windows, MacOSX, Linux, FreeBSD, SOLARIS and other unix and BTRON and T-Engine. This is open and free (under MIT/X Consortiun Lice
A collection of machine-checkend mathematical proofs
The Archive of Formal Proofs is a collection of proof libraries, examples, and larger scientifc developments, mechanically checked in the theorem prover Isabelle. It is organized in the way of a scientific journal. Submissions are refereed.