Doctors have long dreamed of delivering drugs to specific parts of your body, and they may soon have a clever way to do it: fish. UC San Diego researchers have developed nanoscale metallic fish (they're just 800 nanometers long) that could carry medicine into the deeper reaches of your bloodstream. Each critter has a gold head and tailfin, as well as a nickel body joined by silver hinges. You only have to subject them to an oscillating magnetic field to make them swim -- there's no need for propellers or a passive (read: slow) delivery system. That, in turn, could make the drug carriers smaller even as they move quickly.
The technology definitely has its flaws. It's not currently biodegradable, so you may be stuck with this school of fish unless there's a way to flush them out. Gold and silver aren't the cheapest metals, either. Scientists are working on biodegradability, however, and they're hopeful that it will be useful for more than just guiding drugs. You could use to control individual cells, for example, or conduct certain forms of non-invasive surgery. It may just be a matter of refining the technique before you can get medicine exactly where you need it.