Today's most powerful computers rely on a series of processors working in tandem, also known as cluster computing. According to the Top 500, the BlueGene/L holds the honor as the fastest computer currently in use. The BlueGene/L is actually made up of over 65,000 computers with 131,072 processors capable of running at 367,000 GFlops (billions of floating point computations per second). Its primary purpose is the testing and maintenance of nuclear weapons. In order for a computer to be considered for the Top 500, it must be run against the High Performance Linpack Benchmark and solve a random and dense series of linear equations.
Cluster computing has been around since the early 1960s, but it wasn't until the development of UNIX and TCP/IP (circa 1973) that the idea of instant supercomputers came into effect. Programs like Beowulf and Parallel Virtual Machine have made it possible for many computers to join resources. One of the largest projects is SETI@Home where users can allow their computer's spare cycles to search radio transmissions from space. This effort is totally collaborative and the "payoff" is that your home computer may be the one to discover extraterrestrial life. Cluster computing is a more efficient and cost effective alternative to the giant supercomputers of the past.