- 1000 Planets (Mars colony interest)
- Anansi Spaceworks
- Aerorocket - CFD software for rocket engine computer modelling
- Aerospaceguide Net
- Affordable Space (Promotion of cost-effective incremental space programmes) - defunct?
- Ames Mars Atmospheric Modelling Group (using MM5 meteorological model))
- Astronautics and Spacecraft Design - Prof. Mike Gruntman
- Beagle 2 Website :-(
- Clear Sky Institute (Xephem - planetarium for Unix computers)
- Euro-space (site for European space industry collaboration)
- Everything Space
- Extra-solar Planets Encyclopaedia
- Fuelcellstore.com (Hydrogen as an energy source)
- GAO Associates (Aerospace design analysts)
- Gunter's Space Page
- Hubert Astronautics
- Hybrid Rockets eAc
- Incredible Adventures (Book your trip to the ISS here, amongst other adventures, too!)
- International Space Exploration and Colonisation Corporation
- New voyage News (Space tourism & commercial space news)
- Oklahoma Space Industry Development Authority
- Online Universe
- OURS Foundation
- Permanent (Asteroid mining and commercialisation)
- Red Colony (Mars colonisation)
- SETI Institute (Listening for extraterrestrial radio transmissions)
- Space Settlement Initiative
- Takeoff Technologies
- Tech Dreams Impossible Machines (Discussion of spaceplane projects)
- The Earth & Space Foundation
- UK Rocketman
- VACCO Aerospace Products (components for rockets, etc.)