0.01% of a bazillion is still quite a bit
Clay Shirky writes in Wired about the meganiche, a narrowly focused area on the web that can still be very active and significantly popular
I first encountered the meganiche concept by chance: I was examining the top few thousand sites listed by Alexa. Once I had culled the well-known media outlets, famous brands, Web marketing firms, and porn venues, I was left with an unfamiliar, difficult-to-characterize residue. There were focused communities (HowardForums and Gaia, plus sites like CollarMe, LifeTips, and SwapperNet), silly diversions (Consumption Junction, Funny Junk, I-Am-Bored.com, Shoosh Time), narrow commercial offerings (NextPimp, YachtWorld), and creative forums (4Chan, FanFiction.net, and YTMND.com).
Many of these sites are unconventional in their approach, content, and design, but all garner substantial traffic. And traffic means potential revenue, which makes the meganiche a good business bet as well as a cultural phenomenon. User-generated content is the Web-biz buzzword of the day, and meganiche sites tend to produce lots of it.