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.
SVL (System Call Virtualisation Layer) is a C++ library that can be used to detect, abort, and rewrite system calls. The possible uses include, but are not limited to, studying the system call trace of a program; sandboxing a program to tighten security; or selectively rerouting system calls, such as file operations, to different paths or even different sytems to create distributed architectures. SVL allows you to change the low level constructs for system call invocation by allowing you access to both the registers and the target program's memory. As well as having the low level access, SVL has high level classes for dealing with the major syscall operation types.
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.