This might look like a regular old USB cable (with a huge bit to grab to unplug), but it's not a device-to-host cord: its features really shine through (read: only work) when you use it to tether two whole computers together!
Isn't it weird that in this day and age, in the beginning of the 21st century, we still don't have a sane way of moving files and clipboard content between two computers? Intra-network file-sharing is always hit-or-miss, and file-transportation services like Dropbox and Pastefire require a third-party service to serve as the bridge between the two PCs - as USB thumbdrives and SD cards require a whole separate device to truck files over from one computer to the other. What's up with that?
This male USB-A to male USB-A cable actually solves all of your move-files-from-one-computer-to-another problems, especially if you tend to use multiple computers for all your work tasks. Plug it in and your cursor can suddenly, magically, amazingly cross over onto the other computer as if you had simply connected two monitors to the same computer! You can transfer files between two computers that way, by dragging from one desktop to another as if you're just moving it between two folders on the same machine.
And that's not all! This cable also lets you share clipboards across your two computers, enabling you to Copy on one computer and Paste on the other! Moving blocks of text between two word processor documents on two different computers, or from a browser on one computer to a wordpad on the other, couldn't be easier.
As if the above two features doesn't make you throw money at the screen, you can also control one of the connected computers with the keyboard and mouse of the other computer, negating the need for a whole separate KVM switch to use one set of K&V with two computers.
This cable works between any combination of Windows and OS X computers, laptops and desktops, and even slate and tablet PCs.