Darpa Is Developing a Search Engine for the Dark Web | WIRED

An additional detail, from Sleuthing Search Engine: Even Better Than Google? (WSJ): "Unlike many other tools, though, it is free of charge for those who want to download, distribute and modify. Dr. White said he wanted Memex to be free “because taxpayers are paying for it.”"

"But the creators of Memex don’t want just to index content on previously undiscovered sites. They also want to use automated methods to analyze that content in order to uncover hidden relationships that would be useful to law enforcement, the military, and even the private sector. The Memex project currently has eight partners involved in testing and deploying prototypes. White won’t say who the partners are but they plan to test the system around various subject areas or domains. The first domain they targeted were sites that appear to be involved in human trafficking. But the same technique could be applied to tracking Ebola outbreaks or “any domain where there is a flood of online content, where you’re not going to get it if you do queries one at a time and one link at a time,” he says."

From the program introduction (2014/02/09):

"The Memex program gets its name and inspiration from a hypothetical device described in “As We May Think,” a 1945 article for The Atlantic Monthly written by Vannevar Bush, director of the U.S. Office of Scientific Research and Development (OSRD) during World War II. Envisioned as an analog computer to supplement human memory, the memex (a combination of “memory” and “index”) would store and automatically cross-reference all of the user’s books, records and other information.
This cross-referencing, which Bush called associative indexing, would enable users to quickly and flexibly search huge amounts of information and more efficiently gain insights from it. The memex presaged and encouraged scientists and engineers to create hypertext, the Internet, personal computers, online encyclopedias and other major IT advances of the last seven decades." 

Darpa Is Developing a Search Engine for the Dark Web | WIRED