Mail Order:
Squadron Mail Order
Sprue Brothers
Scale Hobbyist
Mega Hobby
Free Time Hobbies
Hobbylinc
Jadar Hobby in Poland
Lucky Model in Hong Kong
Hobby Easy in Hong Kong
Starship Modeler store
Tower Hobbies

General Hobby sites (some with stores):
The Modelling News
Starship Modeler
Beyond the Sprues
What If Speculative Scale Modeling
Modelstories (in French)
Modellversium (in German)
Modeling Madness
Aircraft Resource Center
Hyperscale
Armorama
Ninfinger Productions Space models, among others.
Internet Modeler
Fantastic Plastic
Culttvman
Adrian S. Bruce's Art & Technology

Slashdot
reddit
Wikipedia
Dangerous Prototypes
Hack a Day
Lifehacker
xkcd
Ars Technica

MST3K.com The official Mystery Science Theater 3000 site
Can't get enough Futurama - The Glorious Hypnotoad will be pleased if you visit this site.
The Lurker's Guide to Babylon 5
LASFS: Los Angeles Science Fantasy Society
Satellite News - Official MST3K fan web site
Deux Ex Machina - just about Everything MST3K is here

US Air Force Museum, Wright -Patterson AFB
National Air and Space Museum
Planes of Fame Museum
Nurflugel (Flying Wing) Web page
The Me163B Komet
Blackhawk Down

New Scientist Good place to read up on the latest in science
Eureka Alert
Science Hobbyist
Breakthrough Propulsion Physics Program
ImageJ an excellent, free image processing program
KiCAD is a free PCB EDA program
Eagle is a PCB layout and routing program
The Last Word Science Questions and answers
John Cramer's "The Alternate View" Great essays about cutting edge science
David Deutsch's Home Page Quantum computing and Multiverses...(multiple universes)
Pete Stark's page Pete's 6802 articles in Kilobaud and other work taught me a great deal.

Astronomy Picture of The Day
Centauri Dreams
Sky & Telescope Magazine
Extrasolar Planet Encyclopedia
Extrasolar Planet Search
The Nine Planets Surf Titan! Ski Mars!
Mike Brown's Planets
Relativity and FTL Travel
The Digitized Sky Survey Make finder charts...or surf the Universe.
3D Star Maps Great page! 3D maps of the sky, source code, other Astronomy stuff
Celestia is a fantastic, free real-time space simulator
Starry Night Planetarium Software
Voyager, a Macintosh Planetarium program
Home-built CCD Camera Excellent design, can use either a TC255 or TC237 (in French)
Steve Bedair's DS Powered Telescope Mounts
Telescopes and Telescope Making Mel Bartels' excellent page
Fermi Paradox and Percolation Theory by Geoffrey Landis
Handbook of Space Astronomy & Astrophysics
Space Ref Current news about space
Encyclopedia Astronautica
Ned Wright's page Ned has excellent tutorials on Cosmology & Relativity

vMac - The Virtual Macintosh Emulator Project
Basilisk II An Open Source 68k Macintosh Emulator
SheepShaver is an Open Source PowerPC MacOS run-time environment.

Rowena's Page Short stories by S.D. Youngren. I like them.