Mail Order:
NKR Models Great prices on mostly aircraft & armor kits and amazingly quick shipping
Squadron Mail Order
Tower Hobbies
Sprue Brothers
Mega Hobby
Great Models
Starship Modeler store

General Hobby sites (some with stores):
Starship Modeler
What If Speculative Scale Modeling
Hobbytalk
Modelstories (in French)
Modellversium (in German)
Modeling Madness
Aircraft Resource Center
Hyperscale
Ninfinger Productions Space models, among others.
Internet Modeler
IPMS Stockholm
Fantastic Plastic
Culttvman
Adrian S. Bruce's Art & Technology
Tony Matteliano's Scale Model Index

Slashdot
digg
Wikipedia
Memepool
Consumerist
Pete Stark's page Pete's 6802 articles in Kilobaud and other work taught me a great deal.

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
MST3K.com The official Mystery Science Theater 3000 site
Satellite News - Official MST3K fan web site
Deux Ex Machina - just about Everything MST3K is here

US Air Force Museum, Wright -Patterson AFB
NASM
Paul E. Garber Restoration Facility
Planes of Fame Museum
Russian Aviation Page
Nurflugel (Flying Wing) Web page
Dan Johnson's Web page (Luftwaffe '46 and German Jets)
The Me163B Komet
Aeroplane Books
Blackhawk Down
Gulf War photo Gallery

New Scientist Good place to read up on the latest in science
Eureka Alert Breaking news in Science
Society for Amateur Scientists
Science Hobbyist
Breakthrough Propulsion Physics Program
MathPad is a general purpose graphing scientific calculator for the Mac
NIH-Image Image and ImageJ are excellent, free image processing programs
Eagle is a free PCB layout and routing program
The Last Word Science Questions and answers
John Cramer's "The Alternate View" Great essays about cutting edge science
The Transactional Interpretation of Quantum Mechanics
David Deutsch's Home Page Quantum computing and Multiverses...(multiple universes)

Astronomy Picture of The Day
Centauri Dreams
Sky & Telescope Magazine
Extrasolar Planet Encyclopedia
Extrasolar Planet Search
Extrasolar Visions A truly beautiful Web page!
The Nine Planets Surf Titan! Ski Mars!
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
OSLO EDU A free optical design program
CCD University
Telescopes and Telescope Making Mel Bartels' excellent page
Fermi Paradox and Percolation Theory
Handbook of Space Astronomy & Astrophysics
Space Ref Current news about space
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.
red-agnes has some unusual and wonderfully weird pages. I especially like the Albanian Secret Service identity card.