My two cents: please, PLEASE bring your cell phone (I know it's a little late, since cell phones are three pages back). This is if you get injured and are turned back (there's a small chance of that happening, but it still happens). It's also if you decide to leave the Academy on your own during Basic.
I was with 2011 and ended up being turned back. There's a pay phone in transition flight (which is where you're sent to outprocess once it's decided you're leaving), but you'll need a calling card to use it. The only other way we could talk to our parents/doctors was by cell phone. I didn't bring one because I thought "hey, I'm going to probably get it back in September and can get a better one with a strong signal". Bad idea. And you will need the cell phone to tell your parents when you're coming home so they can come get you. You'll get everything back you came with on I-Day- clothes, cell phone, I-pod (yes people actually brought I-pods), books, etc.
Also bring money. Not only for the pay phone (if you didn't bring a cell phone), but your best friend in transistion flight is food and magazines (and we were able to read the last Harry Potter book before all our classmates

They sold it in the C-Store for twenty dollars or something), because other than one tv, there's nothing to do there unless your cadre is nice enough to let you borrow their laptop (but they're mostly sophmores assigned to Beast Prep, so they're pretty nice). Also, I know some basics got to go to the library earlier on, and I think the gym.
It's not a pleasant topic, but I figured it's valuable advice.