[libvirt-users] web frontend for managing libvirt servers

Hi all, I know that redhat has some web based GUI for managing libvirt clusters, however, I am not having purchased redhat :-) Is there any good open-source web frontend you can recommend for managing your libvirt instances? Ideally with VNC/spice support for connecting to the remote? I know of proxmox, which we used so far for our openvz containers, but I am about to migrate to KVM (and possibly linux-vserver / LXC). Many thanks, Christian.