Australian anime publisher Siren Visual have recently announced via their Facebook Page that for the month of December, all titles available on their official website can be picked up for 20% off by using the promotional code DECEMBER2012.
Siren Visual have released several titles over the last couple of years ranging from their own Australian exclusive anime releases (Dennou Coil, Higurashi no Naku Koro ni Kai, Black Rock Shooter etc) to other interesting titles from Clannad and Angel Beats to Shiki and DuRaRaRa!!. Check out their offiical website HERE.