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We're starting to see a trickle of e-mails from newly minted BAs who -- having experienced a week of the Real World® -- are terrified and want to go back to the ivory towers of academia.
I think most faculty encourage prospective graduate students to contact them. One of the most important things in graduate school is a good working relationship with your mentor/advisee/chair. It behooves you to contact faculty who are working in the same geographical or topical areas at potential universities to see if they might be interested in your research project.
However..... and this must be said .... don't forget that you should be on your best behavior as well as most formal when writing to faculty that you don't know. This means writing your initial contact letter as if it were a paper letter.
I know it seems pretty stuffy but you want to get off on the right foot, right?