libmodbus is a software library for sending/receiving data according to the Modbus protocol. It is written in C and supports RTU (serial) and TCP (Ethernet) communications.
libsigrok is a shared C library which provides basic hardware access drivers for logic analyzers, oscilloscopes, MSOs, multimeters, dataloggers, and more. It also provides input/output file format support.
An Ubuntu-based MySQL appliance that is easy to use and lightweight (152 MB).
A foreign function call interface using small assembly kernels.