I've published libffidemo, a simple C source file meant to be built as a shared library, and DemoFFI, a Smalltalk package that calls libffidemo to, well, demonstrate Pharo's new Unified FFI. DemoFFI was originally published on Smalltalkhub; Damien Pollet kindly repackaged the Smalltalk code, wrote a Makefile for the C source, etc and now libffidemo is a single self-contained repository with all necessary source files. The unit tests serve as the examples. Known working on Linux and OS X.