SPICE provides fast remote desktop connections to guests of implementing hypervisors, e.g. QEMU and KVM.
Quoting the project site:
The Spice project aims to provide a complete open source solution for interaction with virtualized desktop devices.The Spice project deals with both the virtualized devices and the front-end. Interaction between front-end and back-end is done using VD-Interfaces. The VD-Interfaces (VDI) enable both ends of the solution to be easily utilized by a third-party component.