You may have seen left-handed tools; pliers, drills, can-openers, what have you. You may not have seen left-hand thread light bulbs! They're basically the same as any other standard incandescent save for the base: it's backwards, which makes it easier to install and remove light bulbs in left-hand thread sockets. I suppose if someone wanted, they could construct a house that is fully left-hand friendly, and "socket to" all the righties!
Having known a lot of left-handed people, I've heard many of their laments. "Why isn't this available in a left-handed version?" they ask, or "Nobody cares about left-handed people." This is not true, evidenced by the many left-hand products on the market. I've even seen left-handed mice and keyboards, which were quite interesting and allowed me to experience the frustration of left-handed people using right-handed equipment.
The left-handed versions of tools, computer equipment, and the like make perfect sense, but with something like a light bulb it makes less sense. Spherical objects have no prominent side, and so there is no advantage to being left-handed or right-handed when installing/removing them as far as I can see. I wonder why this bulb was made, especially when it also requires its own "backwards" socket?
I found out why! Dave McLellan, the boss man here at eLightBulbs.com, explained that certain applications require a very special bulb with specific voltages and wattages. In such applications, if a normal light bulb were to be installed and turned on, it would instantly fail, potentially exploding and causing all manner of mayhem. Left-hand threads and sockets were created to prevent such situations. The bulb I've linked in this post isn't one of the special voltage bulbs; perhaps at some point the special bulbs were no longer needed but people still enjoyed the left-hand thread. Who knows?