The Japanese website, Tech-On!, has reported that TDK is developing 200GB Blu-ray disc media. According to the article, these 200GB discs contain six layers, with each layer capable of storing 33GB.
TDK Corp. has prototyped a recordable Blu-ray Disc medium with its capacity increased to 200 GB by stacking six recording layers. The new medium boasts the capacity approximately eight times that of the existing single-layer Blu-ray Disc medium.
TDK prototyped a 100 GB recordable medium having four 25 GB recording layers stacked on one another in 2003. This time, the company employed a different signal processing scheme to increase the capacity per layer to 33.3 GB, while increasing the number of the recording layers to six through the adoption of a novel recording material.
I have to give TDK credit. They're really pushing the limits of Blu-ray technology. If you'd like to read more, the entire article can be found here.