One of the first things I often hear is I have never heard of a Sock Machine !  What does one of these machines do ?
The simple answer is,  it makes socks.  But much more then that, a sock machine is an antique,  these machines are about 80 to 100 + years old.  They are no longer being made,  so each one you find is old and has it's own history behind it.  Someone back in the late 1800's or early 1900's owned it, and worked at home to make socks for the men in the war, and earn some extra money.
You can also knit mittens, scarves, and various other items on them.
Another common question is can I make a heel and a toe with a sock machine ?  The answer is Yes, both can be made on the machine.  The size of the sock can be made to fit large feet and small feet.  You can make knee socks, ankle socks, dress socks, men's, ladies, ribbing, and you can even use the Fun Fur to make fancy cuffs. 
A sock can be knit in about an hour on a sock machine.  So if you have a large sock yarn stash, a sock knitting machine might be for you.  Or if you do not know how to knit, but like hand knit socks you will enjoy a machine.  Many people with the machines also sell the socks for $20 + a pair.
Another common question is what kind of yarn can I use on a machine ?  You can use any of the many self patterning sock yarns out now, which are a Sock weight, you can also use Sport weight yarns.  And on the the 54, 56, 60 slot cylinders you may also use Worsted weight yarns.  When using the thicker yarns you will have to loosen the tension.  Very nice mock ribbing can be done with worsted weight yarns.  Some of the popular sock yarn you can use are Opal, Regia, Lorna's Laces, Trekking XXL, Fortissima, and also Alpaca.
Follow along below and I will walk you though how a sock is made.  It does take some time working with a machine to get the hang of the process but after you learn, these machines are a joy to use.  There is a wealth of information also on the Yahoo Sock Knitting Machines group with over 600 members you are sure to find the information you need. 
We even have a annual conference where you can attend classes, meet other people with sock machines, and 'crank' for a couple days and learn all you desire.  See the CSMSA page for more information about joining and attending.