PETSc is a suite of data structures and routines for the scalable (parallel) solution of scientific applications modeled by partial differential equations. It employs the MPI standard for all message-passing communication.

pgRouting extends the PostGIS/PostgreSQL geospatial database to provide geospatial routing and other network analysis functionality.

The POCO C++ Libraries are a collection of open source C++ class libraries that simplify and accelerate the development of network-centric, portable applications in C++. The libraries integrate perfectly with the C++ Standard Library and fill many of the functional gaps left open by it.

DPDK is a set of libraries for fast packet processing. Applications run in user-space and communicate directly with dedicated network interfaces.

PCMemTest is a stand-alone memory tester for x86 and x86-64 architecture computers. It provides a more thorough memory check than that provided by BIOS memorytests.

libfolks is a library that aggregates people from multiple sources (eg, Telepathy connection managers and eventually evolution data server, Facebook, etc.) to create metacontacts.