[1], the Bochs IA-32 Emulator Project, by Kevin Lawton et al.
[2], Valgrind, an open-source memory debugger for GNU/Linux.
[3], the EM86 x86 emulator on Alpha-Linux.
[4], DIGITAL FX!32: Running 32-Bit x86 Applications on Alpha NT, by Anton Chernoff and Ray Hookway.
[5], The User-mode Linux Kernel.
[6], The new Plex86 project.
[7], The VMWare PC virtualizer.
[8], The VirtualPC PC virtualizer.
[9], The VirtualBox PC virtualizer.
[10], The Xen hypervisor.
[11], Kernel Based Virtual Machine (KVM).
[12], QEMU-SystemC, a hardware co-simulator.