Security: Properly Erase Your Physical Media
erase files forever, nuke HD hard driveCodyssey.com - Free shredder
An ordinary deleting of files isn't enough! When you wish to delete any sensitive information, like industrial secrets or some unwanted content, you want to be sure that it will be deleted permanently. Sorry to say, there is a plenty of software recovery tools that can restore your deleted items. If you need to destroy any data and eliminate any possibility of its restoration you need a "shredder". This software destroys the data you choose before the deletion, using a complicated procedure of filling the actual content with random data.
Free document shredder (download)
Hard disk erasing utility (so deleted file cannot be recovered). Similar software: "Eraser", see http://www.heidi.ie/node/6Eraser Portable | PortableApps.com - Portable software for USB drives
Portable para borrar datosLeave No Trace: How to Completely Erase Your Hard Drives, SSDs and Thumb Drives - Data wiping - Gizmodo
Data Permanent Eraser
"With stories abounding of identity theft aided by information lifted from discarded storage devices, you want devices you no longer plan to use to have no usable information when they head out the door. Here's how to wipe them clean."
Leave No Trace: How to Completely Erase Your Hard Drives, SSDs and Thumb Drives - Data wiping