Sabine Hauert of Bristol Robotics Laboratory and Sangeeta Bhatia of MIT are working on giving nanoparticles a sort of swarm intelligence they could use to target tumors in the body as a team. A single nanoparticle may not have much power, but a horde of them could hunt down cancer cells and deliver drugs on target.
Since nanoparticles are just a few atoms across, there's no room to attach a CPU to give them instructions. So the scientists are using magnetic fields to guide the nanoparticles toward a target destination. For now, much of their work is in the simulation stage, measuring the best shapes and tactics to keep the nanoparticles from running into each other and failing their mission.