Rewriteable Holographic memory

By using lasers to etch data onto fragments of a microbial protein, researchers at the University of Connecticut may have demonstrated a way to produce rewritable holographic memory. Holographic memory stores data in three dimensions instead of two and could make data retrieval hundreds of times faster. The first holographic-memory systems have recently come to market, but they do not yet feature discs rewritable in real time.
Researchers at the University of Connecticut, Storrs, led by Jeffrey Stuart, head of the university's Nanobionics Research Center, based their holographic storage system on reengineered versions of proteins produced by bacteria-like organisms commonly found in salt marshes. Simply shining blue light on the proteins erases any data stored in them.

http://www.technologyreview.com/Infotech/19228/?a=f