I just watched the trailer for The Exorcism of Emily Rose, and I have to say that at this point it looks like the first really worthy successor to The Exorcist since, well, The Exorcist.
It's based on the only case of demonic possession ever recognized by the Catholic church.
The trailer is quite creepy and the film looks to be a high quality production that is depending on good acting and story instead of "jump scenes" to creep out the audience. I might just have to check this one out.
The Exorcism of Emily Rose opens September 9th.