The Databank is an external 3.5" hard drive bay that is designed to plug into the PlayStation 4 and sit on top of the unit and it is designed to look like the PlayStation 4, so it does not look out of place.
The best part of it however is that it is able to let PlayStation 4 owners replace the internal 2.5" hard drive with a 3.5" hard drive. As we know the 3.5" drives are cheaper and able to be purchased in much higher capacities. Of course this also opens the world to performance 3.5" hard drives that could not otherwise be used as the console's primary hard drive.
Like the Xbox One the PlayStation 4 does support the connection of USB 3 hard drives, but you can only currently install games on the internal drive. While replacing the 2.5" hard drive with a larger once isn't a cheap solution as these drives are expensive.
While the solution is obviously not officially supported or endorsed by Sony, it seems to us be quite a good solution. Nyko says that they expect the Databank to retail for between $30 and $40 when it is released.