There are some major research projects that are trying to build silicon computers that work like biological brains. For example, Steve Furber’s SpiNNaker aims to make a supercomputer that can simulate one billion neurons. Some labs are also trying to make real wet biology behave like a computer.
Genetically engineered bacteria can be made to perform some basic calculations, and might one day be programmed to detect and treat inflammatory bowel disease or colon cancer. With billions of bacteria all computing in parallel, these would make a supercomputer in your own gut.