I read over the latest KVM putback log last night, and saw that KVM now supports booting from ISO images that are accessible via HTTP (it uses libcurl under the covers). This is pretty fricking cool, and allow you to boot in recovery mode without requiring local media or PXE, and provides a super easy way to play around with live CD distributions. To use this feature, you will first need to install KVM build 87 from source. Once that is complete, you can add the URL to your qemu-kvm command line:
$ qemu-kvm -cdrom http://disarm.prefetch.net/isos/fedoralivecd.dvd
You can also fire up virsh and “edit” the URL into the XML data. KVM is pretty rad, and it’s amazing how many cool features the KVM developers keep kicking out!