Air
Blastwave Jet Company, Boeing Technology Services - Aerodynamics, NASA General Aviation Propulsion Program, Turbo & Jet Engine Research Laboratories, Ultra-Efficient Engine Technology Program
Space
Antimatter, Electric, Nuclear, Unproven Concepts, Cosmos 1: the first solar sail, Earth-to-Orbit Transportation Bibliography, HobbySpace - Launch, Propulsion & Spaceflight , How Space Exploration Will Work, Interstellar Missions, List of Space Propulsion Methods, Propulsion Research Center, Propulsion Tutorial, Solar-Thruster-Sailor, Swiss Propulsion Laboratory
Beginner's Guide to Propulsion
Tutorial slides on basic propulsion concepts.
Chemical Propulsion Information Agency
Comprehensive site with technical resources, propulsion papers, meetings and events calendar.
Compreactive Propeller (Airscrew).
It is suggested to use the internal space (internal channel) of a rotating blade as a centrifugal flow pump delivering pressurized air in a jet engine located on the blade tip.
Journal of Propulsion and Power
Site contains a searchable Table of contents and information for authors and subscribers.
Propulsion Directorate, Air Force Research Laborat
Information on their research projects, and a propulsion primer
Rocket Science Institute
Offers texts about rocket propulsion and propellants, from black powder pyrotechnics to NASA-scale systems.