http://en.wikipedia.org/wiki/Holographic_Versatile_Disc
Specifically: "These discs have the capacity to hold up to 3.9 terabytes (TB) of information"
That's cool and stuff, but why would you want a 3.9TB disc? Unless they create unscratchable surfaces too. And think of the time it would take to burn one at full capacity. I hope they're inventing super HVD writers too. I'm sure one disc would cost hundreds of dollars since a 1TB hard drive is currently around $500.