Ironically, in the "101 Facts You Must Know to be an Otaku" article.
"75. Piece of the Action
The best-selling first-edition manga ever in Japan is One Piece volume 24. Over 2.52 million volumes were sold, meaning approximately one in every 28 people in Japan has a volume. The volume contains the beginning of a new story arc, right after the conclusion of the epic Skypiea storyline, in which the Straw-Hat pirates travel to an island in the sky."
…so I guess this makes me a "super-ultra-mega otaku" or somesuch crap? Reminds me of when someone sent in a letter comlaining about the dub, and were answered with a letter DEFENDING it and which contained something like "Little Suichi would be fine with Luffy stabbing himself in the face, but Timmy wouldn't." Funny, I could have sworn that wasn't in the anime...
Edit:
Okay, I was a a bit off, but
I remember that made me just a touch mad >.> Full thing here.