The word heatsink has always been one of those unusual words that doesn't quite fit what it actually is. Let's break it down. Heat is a form of energy associated with the motion of atoms or molecules and capable of being transmitted through solid and fluid media by conduction, convection or radiation. To sink is to fall or drop to a lower level, especially to go down in stages, or to make weaker or less forceful. Hmmm... I guess heatsink does work after all.
Regardless of my lame attempt to fill an introductory paragraph, there are many many vendors of CPU coolers (aka heatsinks). Most of them do an adequate job, but only a fine few are worthy of being in a PC enthusiast's rig. Enthusiasts (such as the fine readers of OCModShop) want a cooler that performs beyond the call of duty, because they are usually overclocking their rigs, pushing them to the thermal breaking point.