Excellent magazines such as Salon, New Scientist, Mother Jones, Slate, The Economist, and The Atlantic.
Keeping in touch with Slashdot, BoingBoing, 3 Quarks Daily, Marginal Revolution, The Awl, The Globe and Mail, CBC, Guardian Unlimited, and the New York Times.
Blogs and more at Pharyngula, Inverse Square, Bad Science, Statistical modeling, Discover Magazine, Scientific American, Three-Toed Sloth, Kevin Kelly, Worse than failure, Scott Rosenberg, Acephalous, Lawyers Guns and Money, Dean Dad, Unqualified Offerings, and Not Even Wrong.
It's getting warm in here RealClimate, Open Mind, Rabett Run, Dot Earth, Climate Progress, Skeptical science, Isaac Held, and James' empty blog
Economically speaking Brad DeLong, Paul Krugman, Felix Salmon, Justin Fox, Naked Capitalism, Calculated risk, Curious Capitalist, Worthwhile Canadian Initiative, Mark Thoma, and Angry bear.
Why does every little thing have to be so political? Crooked Timber, Matthew Yglesias, Ezra Klein, Balloon Juice, Washington Monthly, and Gin and Tacos.
Writers writing Peter Watts, Charles Stross, John Scalzi, Neil Gaiman, David Brin, Making Light
E-books Smashwords, Baen, Google, Tor?, Weightless
Strangeness MightyGodKing, McSweeneys
Collective programming in action on the Linux kernel mailing list and lwn.net.
Out on the edge with The Onion, the Annals of Improbable research, the Museum of Bad Art, and fresh post-modernist articles.
Comical graphics and graphical comedy by xkcd, Dilbert, User Friendly, Foxtrot, Shermann's Lagoon, Piled Higher and Deeper, Penny Arcade, Ctrl+Alt+Del, Questionable Content, non-sequitur, SMBC, Bug, and Dresden Codak.
A document on special functions.
Integrals done while you wait.
Shannon's paper on entropy.
STREAM benchmarks, a nice compression page,
IDL pages with the Coyote's Guide, Martin's Library,
Fast Fourier with FFTW