I often like to formulate detailed steps when trying to reproduce a bug or a working setup. VMs are great for this because they can be manipulated easily. To manipulate their disk images I use qemu-img to create new disk images that use other disk images as a backing store. This is what I like to call a "poor man's" way to do snapshots because the snapshotting process is a bit manual, but that is also why I like it; I don't touch the original disk image at all so I have full confidence I have...
