Researchers from the University of Cambridge in the UK have developed the world's first 3D microchip, based on Spintronics technology. The chip basically uses atoms to store and transfer the data - and not electronic transistors. This may lead to 3D MRAM chips that have a large memory density - thousands of times larger than what's available today:

http://www.spintronics-info.com/worlds-first-3d-spintronics-chip-developed-cambridge