I've no illusion of what NaNoWriMo is, it's something I do for fun, nothing more. It's generally where I send ideas I know aren't great to die. When I lived in Chicago, going to NaNo groups (as sad as some of them were to look at) was about the only socialization I had - the sense of community is more important to me than anything I write during it. Having a place to send ideas that I know logically suck, but still want to write, is useful.

I write around 2,000 words a day in various projects (when I write, which is about four days a week), though ironpotato will tell you that I'm perfectly capable of annoying people with far more than that. Generally my writing is research/non-fiction (biographies, working on Christopher Isherwood right now). I've steadily increased this from my original 750 words a day, which I started sometime when I was a freshman in high school.

Also, as OftenBen said, anything that encourages anyone to take an interest in writing is something I'm all for. Not everyone has a dream of publishing a novel, some just want to write - which is perfectly fine with me. I've also never been interested in publishing anything written in a month. It took me about four months to write and edit my book (and it was quite short) to a point where I found it suitable - and now when I pick my copy up and flip through it, I can't stand to read it because we didn't take the ax to it hard enough (not in content, but in writing style).

Writing is about all I've ever been great at, and I enjoy doing it. NaNo is an excuse to write some of the stupider ideas, and I'm just fine with that.