The United States is working on a drug that would cure people after they are infected with the smallpox virus. The concept for developing such a drug is dependent on sorting through an enormous number of likely compounds. This can be done by computer, but it requires an enormous amount of computing power. One solution is to use a grid computer. This is not one computer, but breaking up the calculations required so they can run on thousands of PCs connected to the Internet. This approach has also been successfully used for similar medical research. The popularity of finding a cure for smallpox infection might attract enough Internet users (millions, perhaps) to quickly do the calculations necessary to find the cure. Grid computing is becoming a commercial operation, with companies selling use of their PCs at night and on weekends to companies who will provide the "grids" to research firms that need it. The grids that have been used successfully so far have used volunteers. The best example is SETI, where volunteers allow their PCs to examine signals from outer space for signs of intelligent life.