Just when we thought that there is no room more room on those little bits on a harddisk, Toshiba doubles their density again: http://www.newswire.ca/en/releases/archive/September2007/06/c5819.html 

From their press release:

Toshiba Corporation today announced a prototype hard disk drive (HDD) that uses Discrete Track Recording (DTR) technology to boost capacity to a record-breaking 120 gigabytes (GB) on a single 1.8-inch platter. The drive is the first in the world to apply DTR, a breakthrough technology that boost the areal density of a perpendicular magnetic recording (PMR) by a full 50 percent. Toshiba plans to start mass production of HDDs integrating DTR technology in 2009.