ECMAScript Lexer / Parser / Interpreter / VM / method JIT written in C++
Modular, opensource, high performance G-code interpreter and CNC controller written in Object-Oriented C++
An interpreter for the Lua language, written entirely in C# for the .NET, Mono, Xamarin and Unity3D platforms, including handy remote debugger facilities.
The indiscriminate bicurious interactive python interpreter (bpython + ipython)
a functional programming language and interpreter written in GNU Bash 4