Here is a very interesting chart showing off how we got from the Wax Cylinder (yes, people recorded music on wax cylinders!) to the 120 Gb iPod. In the chart you can see a stylized image of the device and how many minutes can be recorded on it. As an extra, you'll get to find out how many CDs can fit into your iPod and you'll also see that your 2TB Hard Drive can hold as much music as 17 120Gb iPods!
Read more and see a bigger chart on Gizmodo