Deus Ex Macchinina
A tiny Cloudstack linux template for diagnostic and testing.
The disk image takes 50MB (20MB compressed) and it can run in as little as 48 MB of memory.
It can deal with Cloudstack instance features such as root passwords, ssh keys and user data scripts.
If you haven't enabled the password feature for the template, then you can login with: root / password
It includes paravirt drivers for all major hypervisors.
Download from http://dl.openvm.eu/cloudstack/macchinina/