GE just announced that they're fitting 500GB of data on discs the size of DVDs through "holographic storage" technologies. It's OK to be a bit lost. This clip explains the idea in more tactile terms.
We've been hearing rumblings of holographic drives and media for years, but now they're actually on the way, ready to be shipped this year. We saw some of these holographic storage prototypes at CES, where 515GB of data can be shoehorned onto a square inch of disk space.