My former colleague Robert Schleicher and his team at Quality and Usability Lab (TU Berlin) has released a set of OpenSource tools to capture and visualize Electroencephalography (EEG) signals from Emotiv EPOC and BrainVision BrainAmp devices. Take a look at the project page for more information and downloads.
Example clients receiving EEG data via Open Sound Control have been implemented in vvvv and SuperCollider. The binaural sonification of EEG signals using these tools is shown in this nice video
