Advanced Space Transportation Program - NASA MSFC: The Marshall Space Flight Center in Huntsville, Alabama, leads NASA's initiatives to dramatically improve access to space.
Breakthrough Propulsion Physics Program: Experiments and theories regarding the coupling of gravity and electromagnetism, the quantum vacuum, hyperfast travel, and superluminal quantum effects.
Emerging Possibilities for Space Propulsion Breakthroughs: article by Marc.G.Millis
NASA Jet Propulsion Laboratory Technical Reports Server (JPLTRS) v2.0: enter 'propulsion' into search and get 100+ reports
NASA Stennis Space Center: Where NASA tests rocket engines.
Warp Drive When?: Have you ever wondered . . .