We've seen some ridiculously tiny electronics in our day, but this might take the cake. Swiss researchers have built an optical networking switch so small that it's measured on the atomic scale -- in fact, it's smaller than the wavelength of light it needs to transmit data. The system can use just one silver atom to transmit an electrical current between silver and platinum pads. Apply enough voltage and the atom moves into place; stop and the atom shies away. Surprisingly simple, isn't it?
Any real-world uses will take a while. The current technique only builds a usable switch one in every six tries, and it's currently very slow -- it can only handle megahertz-class frequencies at best. It should be worth the "few years" of refinement need to make something practical, though. Besides dramatically shrinking the size of an optical switch (what you find in a data center is typically inches wide), it'd create a truly digital signal -- you can't get more binary than the presence or absence of a lone atom. You could one day see switches that behave just like transistors, opening up possibilities that were closed until now.