Parallel computing is especially useful for neural network training. I have trained some neural nets for as long as a week. I have trained 3 or 4 of these at one time on 3 or 4 conventional computers. I have enough computers that I could train at least 10 neural networks at a time, giving a factor of 10 speedup. This is useful for training preprocessor networks, expert neural networks, voting neural network classifiers, modular neural networks, etc.