Holographic Dark Energy and Present Cosmic Acceleration
  We review the notion of holographic dark energy and assess its significance in the light of the well documented cosmic acceleration at the present time. We next propose a model of holographic dark energy in which the infrared cutoff is set by the Hubble scale. The model accounts for the aforesaid acceleration and, by construction, is free of the cosmic coincidence problem. 
Diego Pavon and Winfried Zimdahl