Like I said, they organize local write-ins every now and then, so cookies are totally a possibility, depending who's in charge XD Seriously, though. They've got a tracker so you can see how you're progressing (It's about 1667 words a day to hit the 50,000). Each day (or whenever you want) you copy/paste into a word counter box. It may differ a bit from the word count listed on Microsoft word, for example, so that's something to account for. There are places in the forums to post and get feed back, or coordinate a writing group. And if you reach the 50,000, they do give you a slew of discounts/small gifts. Usually that includes a free printed copy of your work :) That's literally the only reason I did it last year, and for me it was totally worth it. But I also got a nice writing program at half price.
If anyone here does end up doing it, here is my profile: http://nanowrimo.org/participants/daftpirate and you can count on my support!