I decided to use this post to talk about the history of hammers. Why? Why the hell not? It is somewhat relevant, as it is used in the symbol of Communism, and it is also used as an unorthodox method for killing pigs. Lets start:
Early History
The hammer started at least in 2,400,000 BCE when various shaped stones were used to strike wood, bone, or other stones to break them apart and shape them. Stones attached to sticks with strips of leather or animal sinew were being used as hammers by about 30,000 BCE. Its archeological record means it is perhaps the oldest human tool known.
Design
Most hammers now contain a grip, usually rubber or leather, on top of a wooden or metal handle, with the claw and flat end on top.
Specialized hammers of many types were made for particular jobs. Different sizes and designs suited them for tasks ranging from delicately driving in brads to secure small moldings to pounding home the large wooden pegs used to hold together building and ship frames.
Claw hammers were common. Like many hammers, they were dual-purpose tools. The face was used to drive nails, while the claw was used to pull them. 
The peens of riveting hammers were used to spread the ends of rivets or to drive brads in tight spaces. 
Coopers' adzes had an adze blade on one side and a hammer head for driving hoops on the other. 
Shipbuilders' pin mauls were used to drive and countersink spikes and wooden pins. 
Upholsters' hammers had long heads and claws for driving and pulling tacks in hard-to-reach places. 
Lathing hammers had a blade for splitting and cutting lath (wooden strips over which plaster was laid) and a hammer for nailing it into place. 
Mallets and Clubs: Wooden hammers were used to strike tools such as froes, wedges, or chisels that would be damaged if hit with a metal hammer. They also were used to drive wooden joints together. Small wooden hammers were called mallets. Larger ones were called clubs, mauls, or beetles. 