Writing has been one of my passions for almost a decade now. I think it goes back to seventh grade and a story I tried co-writing with a friend in 1998. It didn't pan out terribly well because I hadn't learned a lot about fiction versus ordinary expository writing (which I am pretty good at). I've learned a lot since then.
Getting into NaNoWriMo in 2004 was the big thing for my writing. I'd started one story in 2003 but never got it to critical mass to the point where I could finish (though it remains my favorite, plot and character-wise), and NaNo would be such a catalyst (if we could take previous works into it, which we cannot).
I have attempted it every year since '04, winning twice in four tries.
The goal is 50,000 words in one month. That's do-able; people have written 500,000 in a month. Finishing your story in 50,000 or in November is the hard part. I haven't quite managed that, but when I do have completed manuscripts I'll start posting some of the manuscripts here (and if you ask very nicely I'll email excerpts). I am pretty close to finishing my 2006 NaNo, but I'm about 14,000 words and a climax away.
It's not like they're brilliant; they did, after all, take only a month.