Someone needs to try and draw a big flow chart about how everything is related. Here are the groups/people I am aware of, feel free to add or correct.
1. Main Lost group with Jack, Locke, etc
2. French chick
3. Ethan (deceased?)
4. Others
5. Desmond
6. Kelvin, an unseen character who recruited Desmond to push the button and then died, who also represents the last contact with the Dharma Corporation
7. Secondary Lost group with Shaft and Cupcake, who seem to have gone primitive to stay alive
8. Unexplainable - for polar bears and invisible,whirring and seemingly mechanical devices that grab people and try to drag them down holes
Now how do they all tie together? I have no friggin clue.