Did some R&D for my brother and wanted to document the best options for securely erasing hard drives for sale or donation. Disc Wipe Utility – Windows executable and source (should compile on UNIX/Linux systems).http://sourceforge.net/projects/disc-wipe/ Eraser – Windows scrub utilityhttp://sourceforge.net/projects/eraser/ diskscrub – UNIX source codehttps://code.google.com/p/diskscrub/