"Otaku" in Japanese is usually to refer to individuals who are really into things, whether that be trains, movies, or video games. There are a wide variety of different otaku, but within the last few years the word "otaku" has become shorthand for gaming, anime, or idol diehards.
The stigma surrounding the word is on the decline, and otaku are now viewed as the country's hit makers. Take Akihabara idol group AKB48, which has sold millions and millions of CDs. The group started out as an otaku favorite; it's now mainstream.
Japanese advertising monolith Dentsu is creating an otaku "research lab", the first of its kind in Japan, to studying nerds in hopes of pinpointing their likes and creating the next big otaku hit. In other words, to help churn out more focused tested crap.
「オタク」を研究 ヒット探す嗅覚盗め [産経ニュース]