VirtualBox is a full x86 hardware virtualizer, suitable for server, desktop and embedded usage. It's extremely feature-rich, emulates lots of individual and alternative hardware and devices, supports different virtual machine disk formats, it's cross-platform and supports ancient and current Windows versions, DOS systems, BSD, Solaris and OS/2 as guest operating system.
VirtKick is a simple virtual machine and docker container manager. It provides a VPS orchestration web dashboard, based on Ruby Middleman, and a backend with a JSON API to libvirt/KVM. Virtual machines can be run across a local network of servers.
Cmajor is an experimental programming language. It mixes concepts and language semantics from C++ and C# for semantics. It runs on a virtual machine (cmx) after compilation (cmc), and comes with a debugger (cmxdump). It's itself implemented in C++98 using soul2cpp, provides 64bit integer types using boost, comes with filesystem, shared pointers and threading interfaces. It's cross-platform and comes with an extensive manual.
Zilog Z80 is a C++ shared library and frontend for emulating the like named home computer system. It simulates all hardware pins of the Z80 chip (which was binary compatible to the i8080), and comes with a CP/M 2.2. emulator accessible vis telnet client. It alsp provides an disassembler and instruction set examiner, a ZX-80 and TK-80 emulator.