I've nano'd for 3 years, this will be my fourth.
2008 - This was my first year so I wasn't sure what to expect. I think this was my best year regarding getting into the spirit of NaNoWriMo. I did some dares and such but I didn't even reach 10k words. :(
2009 - This year was a pretty good year involving my plot. I reached a pretty high word count for my standards [a little over 10k] so, to me, that's good. :)
2010 - Last year. Oh, gosh. I think that this was the best year. I went to my first write-in and handwrote 100% of all I got written. It still has yet to be typed up but I still got 15,000 words. :)