You know what's always impressed me? How much storage space we have, and at such a small spacial cost. I found 3 great examples of this.
First, an old IDE harddisk I had lying around.
Date: 1998 (11 years)
Storage capacity: 3.2GB
Size: 2.5cm x 10.1cm x 14.5cm = 366.125cm^3
Storage density: 366.125 / 3.2 = 144.41cm^3/GB
This anchient machine was manufactured in 1998, and has less space than some thumb drives. Scary, isn't it? Plus this thing needs an external 12v power supply, and has an IDE interface.
Next, a Sony Micro Vault Tiny
Date: ~2006 (~3 years)
Storage capacity: 1GB
Size: 0.2cm x 1.4cm x 3.2cm = 0.896cm^3
Storage density: 0.896 / 1 = 0.896cm^3/GB
Speaking of thumb drives, heres a fully functional USB thumb drive. Even though it has only ~1/3 the space of the IDE drive, it is also an amazing 408.7 times smaller. Hmmm...
Last, a MicroSD card
Date: 2008 (1 year or less)
Storage capacity: 2GB
Size: 0.1cm x 1.5cm x 1.1cm = 0.165cm^3
Storage density: 0.165 / 2 = 0.0825cm^3/GB
I got this with the purchase of my phone in December. This tiny wonder has 2GB of space, in a very tiny package. Its over 5 times smaller than the thumb drive, and has over 10 times the storage density.
Just to give you some ideas, if the IDE drive had the same storage density as the USB drive, it could store 403.6GB of data. And if it had the storage density of the MicroSD card? 4437.9GB, or 4.3TB of data.