Sussex Uni Cognitive Science - useful link for info and many papers on Psychology, Neuroscience, and Linguistics, and many areas of Computer Science (e.g., artificial intelligence, robotics, vison, learning, speech, neural networks), Philosophy (e.g., mind, language, knowledge, science, logic), Biology (e.g., ethology, behavioral ecology, sociobiology, behaviour genetics, evolutionary theory).
behavioural and brain sciences (BBS): great source for academic science articles.
American Scientist magazine - lots of stuff available on net.
Astrobiology web - Extensive information on space, life, evolution and intelligence.
"Stephen Hawking presents" an interesting, well-presented exobiology and SETI site, lots of info.
evolution, complexity and philosophy; excellent site, loads of info.
links to info about interesting scientists; very useful and comprehensive.
'Principia Cybernetica', another handy link; although the contents are overly cosmic/far-out in places, there's loads of interesting and well-written stuff available there.
Science Frontiers Good site, lots of interesting anecdotes. Here's the blurb: "Online version of the monthly newsletter providing digests of reports that describe scientific anomalies in the fields of archaeology, astronomy, biology, geology, geophysics, mathematics, psychology and physics."
'The World of Richard Dawkins', by John Catalano. Lots on Dawkins of course, but also plenty on evolution & science in general.
SciTech Daily Review: a good online assortment of up-to-date science stories & opinion; updated daily. I have it as my homepage.
Bioinfo Animal Pictures Archive— a fantastic source for animal photos. Ici le blurb: "More than 15,000 images !!! Most of the images are from the newsgroups, especially from alt.binaries.pictures.animals."
Marvin Minsky (Mr. AI)'s homepage; lots of info/thoughts from the sage.
A ginormous collection of AI links, from the University of London. Seems like they have everything.
Reality Club, following and promoting some major scientific arguments. Excellent articles by and about scientists, including Dawkins, Pinker, Dennett, Minsky . . .
SETI@home, where you can actually help in the search for extraterrestrial intelligence, by downloading a program that analyzes data from radio telescopes. Shows you some cool graphics & info while the data is being analyzed. Go!
Hibakusha (A-bomb survivor) testimonies. Distressing stuff - some of it left me pretty speechless.
good page on Alife at Sussex Uni - fairly technical.

COMPLETE BOOKS ONLINE

Charles Darwin's "On the Origin of Species": the whole book is on the web here. Still brilliant; the scope of his research is astonishing, and the approach very hands-on.

'Principles of Psychology' by William James (1890). The technical parts can be a little past sell-by, but James was a first-rate psychologist and philosopher of mind. This is part of the excellent Internet resource 'Classics in the History of Psychology', which gives you access to just that.

'The World, the Flesh, and the Devil' by J.D.Bernal: if you like thinking weird stuff on the biggest possible scale, this is for you. I think the man himself disowned it in later years, but it's interesting.

'Engines of Creation', by K. Eric Drexler: seminal and wide-ranging book on how self-replicating nanomachines will revolutionise science, technology and life. Drexler's a strong thinker. Foreword by Marvin Minsky. From the Foresight Institute's nanotechnology page.

Freeman Dyson page. This old geezer is an impressive and interesting polymath. Best links near end of page.
Some of 'The Age of Spiritual Machines' by Ray Kurzweil is online here. It's about the future of machine intelligence.
Sky & Telescope's SETI pages
Science Daily: articles about breaking scientific research.
'PSYCOLOQUY': articles on evolution & philosophy of mind.
AI book reviews from the prolific Danny Yee
Extropian society: (an 'unconventional' bunch, but some interesting ideas & info).
MIT research - they're doing really cool stuff, but the site isn't all that in-depth or informative.
the Setileague articles: SETI League, a bunch of well-informed SETI enthusiasts.
an extensive list of biology/evolution links at the Biology & Evolution Jump Station. Webmaster Phil Jamison pokes fun at Jerry Falwell, which is always a good thing.
list of ejournals at Stanford Uni.
Memetics at the 'thought contagion' home site.
Lucid Dreaming: the ability to realise that you're dreaming, and to control your dreams.
The Florida Entomologist is online (free) here. It's an academic publication about insects.
Have a written conversation with your choice of talking computer programs (chatterbots). Interesting, but the ones I've tried aren't that impressive (compared with humans).
Universe Today: good for info on astronomy, space exploration and planetary science. Updated every weekday.
Links page for internet publications.