My curiosity about IPv6 led me to meander from its Wikipedia entry over to this entry on the Dark Web:
http://en.wikipedia.org/wiki/Deep_webThis was something of more practical interest to me back in graduate school, where I would often search in vain for more or less obscure academic articles online in the hope I could save myself a trip to the library. There were a few closed databases like JSTOR that I gravitated towards as a student in the humanities.
Now, outside the academy, I still long at times for the unfettered access to such databases enrollment at a major university with a well-funded, major research library provided.
The wikipedia article mentions a few services which claim to index the dark web. Tried
goshme.com. Looks potentially useful, or at least novel. I'll have to try it again when I have something darker to look for.