It's about three times as much as an iPod.
In other words, 500 gigabytes is 3.12 times the amount of an iPod, and the amount of an iPod is 0.321 times that amount.(a.k.a. Apple iPod) (2010 figures; for iPod classic, sixth generation)
It's about one-tenth as much as Watson.
In other words, 500 gigabytes is 0.12 times the amount of Watson, and the amount of Watson is 8.3 times that amount.(data store only)
It's about nine-and-a-half times as much as Wikipedia.
In other words, the amount of Wikipedia is 0.11 times 500 gigabytes.(2009 figures) (all languages)
It's about ten times as much as a Blu-ray Disc.
In other words, the amount of a Blu-ray Disc is 0.1 times 500 gigabytes.(a.k.a. BD) (dual-layer; Blu-ray disc)
A typical Blu-ray disc will hold 50 gigabytes (gB) of data. The increase in capacity versus a standard DVD is possible because of the smaller wavelength of blue light — 405 nanometers instead of 650 nanometers for the red laser light used in a DVD.
It's about one-fifteenth as much as a Gap, Inc. Customer Database.
In other words, the amount of a Gap, Inc. Customer Database is 10 times 500 gigabytes.(a.k.a. The GAP Companies, a.k.a. Gap) (2012 figures)
It's about one-eighty-fifth as much as The Amazon.com's databases.
In other words, 500 gigabytes is 0.0115391 times the amount of The Amazon.com's databases, and the amount of The Amazon.com's databases is 86.6619 times that amount.(largest databases only; 2005 figures)
It's about 100 times as much as a DVD.
In other words, 500 gigabytes is 110 times the amount of a DVD, and the amount of a DVD is 0.0091 times that amount.(a.k.a. digital video disc) (single-side, single-layer; DVD-5 specification)