Besides producing infections and making yogurt, it appears that a form of bacteria is potentially useful in data storage. The idea of using bacteria to do computations has been discussed in the past, and now it seems a method has been developed to get a protein from bacteria that is useful for data storage on optical discs. Supposedly, this light-sensitive protein is able to retain 50TB of data on a disc. Scientists in the U.S. are developing this by modifying the DNA of the protein-producing lifeforms:

Since the intermediates generally only last for hours or days, Prof Renugopalakrishnan and his colleagues modified the DNA that produces bR protein to produce an intermediate that lasts for more than several years. They also engineered the bR protein to make its intermediates more stable at the high temperatures generated by storing terabytes of data.
Fascinating stuff, indeed. Don't imagine you'll be laying your hands on a gooey disc that stores oodles of data, however - if it ever pans out, it would likely be just like any other optical disc. Then again, no other optical disc can claim to have future expansion to 50TB.