When used as a machine emulator, QEMU can run OSes and programs made for one machine (e.g. an ARM board) on a different machine (e.g. your own PC). By using dynamic translation, it achieves very good performances
Links:
[1] http://linux.philosweb.com/drupal/category/it/hardware
[2] http://linux.philosweb.com/drupal/category/it/software/os
[3] http://linux.philosweb.com/drupal/category/it/software
[4] http://fabrice.bellard.free.fr/qemu/download.html
[5] http://en.wikipedia.org/wiki/QEMU
[6] http://fabrice.bellard.free.fr/qemu/about.html