Bochs? Since Virtualbox release it has lost a great deal of attention, as VirtualBox is a fork of Bochs. I wonder if all the great things and improvement Virtualbox have received over Bochs have been merged back? It could be a great time to merge back if not. I'd also love to have the Virtualbox GUI with Bochs.
Virtualbox is a fork of Qemu (which I don't believe is related to bochs). Qemu gets boatloads of attention at least in part due to KVM.
Bochs is nice too especially for debugging, but Qemu can do most of that as well, plus user-mode emulation.