Like most geeks, my house is full of old hard drives of various capacity, storage is very cheap these days. In a world where data privacy is an ever increasing issue and money is short you might decide that one day you want to either get rid of these old drives or sell them either over the internet or to your mate who's starting a freenas project.
Whatever you decide to do, it's important to make sure this drive leaves your procession with no possible way of accessing the old data. Of course the best way is to completely destroy the drive physically, however we all know that most people aren't going to bother, if you really have to pass this drive on or sell it you should at least make sure you try out DBAN to remove any traces.
DBAN (Darik's Boot and Nuke) it's a boot disk which will wipe most hard drives using some hardcore data wiping technology, including some American Department of Defence techniques to make sure your data is really gone. When you delete data from a hard drive in a conventional way, there are still ways of recovering this data quite easily. DBAN will pass every section of the drive multiple times to remove references to the old files, the more passes the better.
Head over to the project page http://www.dban.org/, download the boot-able CD then burn the image using your favourite image burning application and your ready to go.
DBAN provides a few different options. I'm a massive fan of DoD 5220.22-M wipe, but it will take a little while depending on the size of your drive.
Each option will give you an idea on the type of security you will get from the erase. This is a great tool for anyone concerned about data piracy, which should be everyone!