Stars
Synopse PDF engine is a fully featured Open Source PDF document creation library for Delphi, embedded in one unit
stb single-file public domain libraries for C/C++
Plataform independent (windows/linux) C++ audio playback library (uses DirectSound under Windows and Alsa under Linux)
Single header SQLite C++ Wrapper (yes, another one, there are many like it, but this one is mine).
A platform independent C++ socket library with transparent SSL support (and some more stuff).
A small and easy to use neural net implementation for C++. Just download and #include!
Sol3 (sol2 v3.0) - a C++ <-> Lua API wrapper with advanced features and top notch performance - is here, and it's great! Documentation:
C++11/14 strings for direct use in template parameter lists, template metaprogramming.