The best Cyber Monday external hard drive discount is WD's Easystore 5TB model. This slim, portable drive is on sale at Best Buy for $89.99 (a $90 discount), less than two cents per gigabyte. Equally important, it can alleviate the game installations that are eating away at primary drives.

That's not the only reason to consider an external storage drive. One of the best uses for portable drives is that they can back up multiple PCs more quickly and easily than other methods. Once you connect the drive to your own PC and copy your important data, you can then do the same thing on other desktops and laptops in your home. Depending on the amount of data, 5 TB of storage would be enough to back up both parents' PCs.

WD's Easystore comes with software for automatic backup. It also connects via USB 3.0 and offers a theoretical maximum transfer rate of 5 Gbps. Actual transfer rates will be slower due to overhead and other factors, but still relatively fast.

The value proposition is even better if you play games on a PC or console, as this portable drive allows you to back up the latter's titles. It's also Mac compatible, so if someone in your household has turned to the dark side, no worries. Finally, this drive is USB-powered, so there is no need to connect a separate power cable.