Really obscure? Really out-of-print? Try the Basement Full Of Books project, which eliminates the middleman by linking readers up directly with authors.
Nanotechnology with Dr. J. Storrs Hall. Similar information can also be found at The Foresight Institute, founded by nanopioneer K. Eric Drexler.
If you're interested by the artificial life / genetic computation / evolution themes in BLOOM, try The Alife Page for cool demos and graphics, then the Santa Fe guys who invented a lot of it, for information, definitions, and links.
For "reality consulting," in astrophysics et. al., try Boris and Bjorn in Denmark. Their black hole page is really something!
An introduction to Libertarianism, because it's good for you.
Cryptography and anonymity issues, courtesy of the Cypherpunks.
Strategy gaming with master game designer Greg Costikyan author of PARANOIA, PAX BRITANNICA, NUCLEAR WINTER, and lots more.
Linguistics, including Esperanto and other constructed languages.
Fans of the "Dream of Houses" series in Analog may get a kick
out of The Micronations
Page, chronicling various attempts, both serious and silly, to buck
the system and start new small countries.
You may also return to Wil McCarthy's home