I am usually the queen of procrastination. The only way I can really make myself do a lot of work is by making myself a really anal and obsessive schedule (I mean like a big chart on work with specific times, activities, and notes about each one, including meals and breaks). I then HAVE to stick to it as closely as possible. For example, today was one of those days where I had insane amounts of school work to get done, and it was necessary to whip up a schedule.
Because I didn't leave my dorm, I tried to make meal times into breaks as well, I watched an episode of Greek on hulu with lunch and dinner and used that as time to check facebook and 3FC. If it is getting really bad, try getting a friend you trust to change your facebook password for you, and only let you change it back once finals or the big paper is over with. I do this almost every midterm/final season. Or I at least log off and don't check it for two weeks or so. It sucks, but the longer you go, the easier it is. And think of all the things there will be to catch up on when you log back on!
When it comes to essays and papers, I think the best way to tackle them is to just start writing. I never start at the beginning, I just pick a point that I find interesting and that I think I can write about and I go from there. Sometimes I'll have a few word documents open on my computer at once all with different bits of the paper. Eventually, when I've said everything I can and it is long enough, I start to piece it together. The opening paragraph and the conclusion are always the last things I write because by the time I get to them, I've formed a solid argument and can better write a thesis sentence and a closing statement. Truthfully, I'd rather write a paper or essay than study any day. I put on good music, and get into a writing grove and am surprised when I've written six pages in two hours or something like that.
My advice, step away from facebook, shut it down for the night and do what you can for the essay. Facebook and 3fc will be there in the morning, but your essay won't if you don't start writing! Good luck!