#5 makes an excellent contribution discussing how the names of the characters can be viewed symbolically. I would just like to expand briefly on how Old Man Warner is a symbol of tradition. He, as the oldest member of the community, is proud of how many times he has participated in the lottery. He is also the one that Jackson chooses to give the words that relate so strongly to the theme of the story - the attractiveness of tradition and how it blinds us to any other possible ways of operating.

The color black has been explored in other answers; however, there are many other symbols, as well.  I teach this story a lot in all of my classes and it is one of my favorites!

A few other symbols that cannot be overlooked are the names in the story:  Mr. GRAVES,  Mr. SUMMERS, Mrs. DELACROIX, for example.  Graves is self-explanatory in that it could represent death. Summers is a symbol because it represents the season the lottery is held.  Delacroix means "of the cross" in French, which is relevant because this is a religious reference in a town who employs a pagan ritual of human sacrifice (and a very old Christian ritual) for a prosperous crop harvest. 

Also, the three-legged stool is another symbol.  It is odd to find a three-legged stool.  Most are four legs, so the fact the author takes the time to mention the three-legged stool adds to the oddity of the story. 

Other symbols are the rocks and pebbles the people throw (a Biblical reference to casting the first stone) and Old Man Warner, who represents tradition and the old way of doing things.

In The Lottery, how was suspense was used and how does the author use it and was it used effectively?

  Suspense is built through the entire process of setting up the lottery box, the selection of the slips of paper.  Not knowing who will get a black dot.  It was very effective. I felt that the sheer horror is created by the acceptance of the town of this heinous act of human sacrifice. 

It is chilling to read the story with the townspeople standing around waiting for the lottery to begin, acting all normal.  Suspense is built because the reader does not know what the lottery is really all about until the end, when the people start throwing stones at the innocent victim. 

Black has always been a color of evil.  The bad guys in westerns always wear the black hat.  :)  Black being the color of night when most evil doers crawl out of their holes in order to do their worst without being seen or caught, the color has always been representative of those who prefer to remain in the shadows.  Death, Satan, thieves, rapists, etc.

So, the spot on the slip of paper is the harbinger of death for the poor players of the lottery. 

The black box itself is a symbol--falling apart, original intent forgotten, meant to be repaired, but forever in disrepair and in service.  It represents the lottery itself...many of the villagers talk of revamping or doing away with it but it is always decided to just continue as they always have.  Tradition for tradition's sake.