I remember watching a video in my high school psychology class about a woman who had seizures, so the last resort solution was to cut her corpus callosum, which joined the two hemispheres of the brain. The video then continued to show the ramifications of the surgery through the various experiments performed on her.
While there were clearly negative effects from the surgery, such as the inability for the right side of the body to react to the left visual field, there were also some effects that, to me, seemed pretty useful.
There seemed to be a splitting of the consciousness, which may sound a bit frightening. But I also thought that if it could be controlled well, could it be possible to have the left and right side of your body doing separate but meaningful tasks at once? I have heard of people who are able to write different sentences with both their left and write hands at the same time. It seems like such training to perform such tasks involve the corpus callosum?
I couldn't find the original video, but this seems close!
http://www.youtube.com/watch?v=aCv4K5aStdU