I was thinking that we could do a mock trial type activity... the students would pick a side--defence or prosecution. Then the class would evaluate each character individually taking into account actions of each as an outcasts and decide if the characters should really be outcasts.
This is just one idea... do you have any others?
Clearly one of the interesting aspects of the story is to what extent are the various characters dynamic and static. The two prostitutes, for example, clearly develop and become more moral and better individuals by the end, whereas John Oakhurst arguably shows that, as the narrator says, he was the least of all the outcasts. You might get students to chart character's development through the story on a graph, linking points of movement to specific quotes or actions.
Secondly, you might like to get students to research into such communities and then ask them as an assignment to re-tell the story in the form of diary entries from the perspective of one of the characters.
Perhaps there could be a soliloquy night; as the individuals lie awake, knowing the dilemma with which they are faced, each one ponders the future.
Soliloquies are always revelations of the inner realities of characters. Let students put into words these various inner realities by writing silent soliloquies.
How about examining the good, Christian people of Poker Flats who wanted to rid themselves of those whom they consider to be unworthy of living in their fine town? Perhaps re-creating the town meeting in which the citizens of this town decide to oust these "undesirables" would promote some interesting discussion.
You could have the students modernize the story. Have them take the general idea and set it somewhere else...a colony on Mars or in King Arthur's Court. The greed, prejudice, etc. would still be there, but like a Shakespearian play, the students would have to be familiar enough with the characters's motives, setting of the story, and plot to put the entire story in another place altogether.
You could give scenes to different groups and allow them to set their individual scenes wherever they want and then have them "act" the story with all the scenes one after another...videotape it to see how the scenes fit together based on characters, motives, plot, etc.
Since the story is set in a mining camp, you might do a project to show how the gold rush affected the economy in the camps. Have you seen the movie "Tombstone"? I think it is so funny that every merchant in town wears a suit and tie--because they're making so much money off the miners. Maybe you could have groups do research on what commodities would have been used and sold and make posters and/or "set up shop" in the room. You could have grocers, butchers, dress makers, saloons, livery stables, blacksmiths, etc.
Take a look at the Topics for Further Study section, linked below, as well.