Nobel Prizes often get awarded to research where practical application is so far down the road that it cannot actually be fathomed by mere mortals. The Nobel Prize for Physics often falls into this category, but not this year. The 2007 Nobel Prize for Physics was awarded to Albert Fert and Peter Grünberg for the discovery of Giant Magnetoresistance.
If you are reading this on a computer or other device with a hard drive, chances are you are using Giant Magnetoresistance right now. The phenomena Fert and Grünberg discovered is what allows the reading and writing of mass amounts of data on a hard disk. Giant Magnetoresistance (GMR) is largely responsible for the increasing capacity of hard drives because it allows more data to be squeezed into smaller spaces.
This IBM animation of GMR at work should give you a better idea of what the discovery has actually means in terms of increased hard drive efficiency and capacity. We cracked open a hard drive apart recently and had a good look at the read/write apparatus.