I did an expository essay for my Crucible SAC comparing and contrasting the characters of Hale and Proctor with the two prominent leaders of the Civil Rights Movement, MLK and Malcolm X. I wish I had it with me to remember the prompt that got me to write about it.
As mentioned previously, McCarthyism from the 1950s served me well as a parallel to the Crucible in a couple of essays.
The idea that absolute power inevitably corrupts individuals leading to conflict could perhaps be a decent idea. It can be linked to the two most prominent Communist nations to exist/have existed, China and Russia, especially when you look at their revolutions. If you like your Shakespeare, Macbeth is a nice example, if you're a fan of Orwell, Animal Farm is another good one.