kvm-simple-init can perform the following actions on a KVM machine: start, stop, kill, and restart. It focuses on simplicity, and is fully implemented in just a few hundred lines of shell script. It is intended for people who do not want to run libvirt just for running a few VMs, or people who prefer to manage flat configuration files using their preferred configuration management system. It does not provide complicated configuration file format or parameters. Only two pieces of information are needed: a QEMU monitor port for the machine and the full KVM command line needed to start the machine (gives full configuration freedom). kvm-simple-init can be used directly as a system init script for starting all KVM machines on a host machine. Just drop it in /etc/init.d, and enable it with the tools provided by your UNIX distribution. kvm-simple-init was inspired by the init script of FreeBSD jails.
libguestfs is a set of tools for accessing and modifying virtual machine (VM) disk images. You can use this for viewing and editing files inside guests, scripting changes to VMs, monitoring disk used/free statistics, P2V, V2V, performing partial backups, cloning VMs, and much more. libguestfs can access nearly any type of filesystem including: all known types of Linux filesystem (ext2/3/4, XFS, btrfs, etc.), any Windows filesystem (VFAT and NTFS), any Mac OS X and BSD filesystems, LVM2 volumes, MBR and GPT disk partitions, raw disks, qcow2, CD and DVD ISO images, SD cards, and dozens more. libguestfs doesn't need root permissions.
OpenNebula is a toolkit to easily build any type of cloud: private, public, and hybrid. OpenNebula has been designed to be integrated with any networking and storage solution and so to fit into any existing data center. OpenNebula orchestrates storage, network, and virtualization technologies to enable the dynamic placement of multi-tier services (groups of interconnected virtual machines) on distributed infrastructures, combining both data center resources and remote cloud resources, according to allocation policies.