I think that a really interesting piece would be to write about Abigail after the trials. The events of the play and those that subsume the town are done out of her initial accusations and continuing the process to envelop more people and casting a wider net. Yet, she ends up fleeing Salem and going to Boston, where she reportedly becomes a prostitute. She is conflicted and yet is the cause of conflicts throughout the play. I think it would be really interesting to hear her thoughts and her impressions of what happened, her role in it, and any reflections she might have afterwards from this point of view. I think that it would be really imaginative for a writer to delve inside her mind, inside her experiences, and explore what made her "tick." Exploring these issues such as the death of her parents, the lack of parental love, the desire of John Proctor, as well as the conflicts surrounding her and what happened as a result might be a highly imaginative piece, guaranteed to increase discussion of the drama and those involved in it.
A good imaginative piece might be a series of love letters between the two secret lovers. Another idea might be to just have John write diary entries.
If you chose the route of letters between the two, you would be able to express Proctor's purpose to break the relationship as well as Abigail's intention to keep it alive. This continuing conflict might show them trying to make deals and compromises with each other. Those efforts might have impacted what ultimately began to happen in the play. I could totally see Abigail telling John that he better do this or that otherwise she would rat on him for witchcraft. He wouldn't believe her and then she would act on that.