Pre-interview stuffs to do

For people who have interviews approaching, here's a short, preparatory (and probably mostly self-evident) checklist for the campus visits:

• If you haven't done this yet, check to see if it is traditional in the department for prospective students to contact potential advisers in advance of the interviews. In some departments (including the three I've been part of), it's really your future adviser who grants you admission, and the department just rubber-stamps their decision. In other places, it's common for students to join without knowing exactly who their adviser will be. Write your potential adviser, if it's appropriate.
• Read the departmental website thoroughly. Try to determine the requirements for achieving candidacy, what kinds of coursework students take, whether there are lab rotations or teaching requirements, and whether there are department-wide policies on how graduate students are funded.
• Read thoroughly the lab websites and personal websites of faculty with whom you are interviewing. Read their CVs. What are their academic backgrounds, and who were their advisers? What fields have the potential advisers published in, and which fields have they published in recently? Do they have tenure, and if not, when will they be up for it? (For outdated websites, you might want to supplement their publication list with searches on Google Scholar, PubMed, arXiv, Web of Knowledge/Science, Scopus, etc.).
• Scan the specialties of the faculty members in the department. Get a sense of the breadth of the department.
• For each faculty member with whom you have a decent chance of working, read the abstracts of all of their papers that you find vaguely interesting. Read thoroughly at least a few papers that relate to work you might do with them. If you don't have access to these papers through a university, it's perfectly fine to email the professor to ask for a "reprint" (which will really just be a pdf). It's better not to do this at the last minute.
• Scan the pages and publications of the grad students, techs, and postdocs in the labs you might join. 
• Figure out who the department chair is.
• Write a cribsheet with this information somewhere and take it with you to interviews. This is really helpful if you're interviewing at a bunch of places back to back.
• Review your personal statement, and use it to develop a list of questions in your field that you find interesting and another list of potential projects. These ideas don't have to be genuinely viable at this point, but they show you're curious and thinking about research, and you can use them as a springboard in conversation to talk about more realistic directions.
• Write down the questions you have about the department, research, etc. (See the posts on meetings with potential lab members and potential advisers for more ideas.)
• Take a notepad and pen with you to your interviews.

Bonus points:

• If your potential advisers are funded by the NSF, look up their current and past grants on the NSF's Fast Lane Award Search. If they're funded by the NIH, check out the NIH RePORTER database. Most private foundations have their own databases too. Sources of funding are usually listed on CVs.
• Look up your potential advisers' most cited publications in one of the citation databases mentioned above to get a semi-objective sense of what they're known for. Also look at who's citing some of their more recent publications--which hypotheses are being debated? Who are their collaborators? Pay attention to any Science, Nature, Cell, PNAS, and Phys Rev Letters publications.

 Are there other preparations that people have found helpful?