John Hopkins University

Developer of a range of spacecraft and scientific payloads providing project overviews, scientific and engineering articles.
http://sd-www.jhuapl.edu/

Space and Astronomy Reference Links

Provides a space and astronomy related directory.
http://www.refdesk.com/space.html

FAST

Provides directory with validated and graphics-free entries, compiled the National Space Society, USA.
http://fly.hiwaay.net/~hal5/space-links.shtml

Russian Space Web

News and history of the Russian space program by Anatoly Zak, a journalist.
http://www.russianspaceweb.com/

Space Travel and Exploration

News, information, and resources about space exploration for the armchair space traveler.
http://www.spacehike.com/

Encyclopedia Astronautica

Comprehensive resource providing articles on most space technology subjects and space flight history.
http://www.astronautix.com

NASA Skywatch Sightings Calculator

A Java applet that will calculate when spacecraft will be visible in the night sky over the viewer's own location.
http://spaceflight.nasa.gov/realdata/sightings/

Space Projects and Info

Offers a collection of popularized material on space projects and astronomy. Includes forums and merchandising.
http://www.aerospaceguide.net/

Heavens Above

Real-time satellite, ISS, and Space Shuttle orbital pass information, maps, and star charts.
http://www.heavens-above.com/

BBC - Space

Features a variety of resources for space exploration and introduction to space flight. Includes many interactive and 3D animated views.
http://www.bbc.co.uk/science/space/index.shtml

Jump from Space.

Features a Russian project to sky-jump from space (over 40km altitude). Includes background of the project initiator, Mogamed Tolboev.
http://www.tolboev.ru/

European Space Industry Directory

ESID is an ESA database of more than 400 space companies and 1000 products.
http://www.esidirectory.org

Usenet space archive

Large collection of google group postings on all aspects of space exploration and development.
http://yarchive.net/space/index.html

SpaceRef.com

Offers updated news selections, directory and collected reference material.
http://www.spaceref.com/

Launchdate

Offers an updated list of coming launches, information about ionizing radiation and related resource links.
http://www.launchdate.com/