Brainstem X

Brainstem is, to my knowledge, the clear choice for neural network applications running natively in Mac OS X. It boasts a polished interface and is very stable. What's more, it is fast, beating out the two other neural network implementations that I tested it against - including the only other OS X native application, whose training epochs take roughly four times as long. Finally, it is free for non-profit purposes. Use it as much as you want, and the only time you have to give me any money for it is if you are using it to help yourself make more money. I am happily soliciting user comments, also, in order to add features in the future; this is software that will grow to fit your needs, if it does not do so already.