a-fedora-appliance is a supermin demonstration Fedora appliance.
I have scratch-built a Fedora RPM here which is just a 235K download but contains (by magic!) a fully bootable Fedora appliance. After installing the RPM in Fedora 20, do the following to boot the virtual machine:
Note that the scratch build will only last in Koji for a few days. After that you’ll have to follow the README file included in the source.