Two types of ESP activity have been the subject of the most rigorous reproducible research:
Micro PK, or Psycho-Kinesis. This is affecting small objects, particularly electrical systems, by using the mind. Researchers had particular success when people tried to influence systems depending on quantum-mechanical effects for their operations, such as Random Number Generators driven by radioactive particle decay. Best reference so far is Margins of Reality by Robert Jahn & Brenda Dunne, which describes their work on PK at the Princeton Engineering Anomalies Research lab.
- Remote Viewing. This is the acquisition of information about people, places, and events located at a distance in space and time. Otherwise referred to as clairvoyance. Most common experiments involve determining the contents of pictures in sealed envelopes, or tracing the movements of an experimenter as he or she moves around the town. Best single reference is Mind Reach by Harold Puthoff and Russell Targ. This describes their research at Stanford Research Institute back in the seventies.
- These two abilities form the basis of useful parapsychological abilities as far as government interest goes. RV has obvious uses in intelligence gathering. Even if it can just suggest a direction to look or an area to concentrate on, it can serve as a valuable adjunct to more conventional methods of intelligence gathering. Modern intelligence gathering techniques produce massive amounts of information, much of it not very useful. RV may be able to focus that collection effort to some degree. At its most reliable and useful, information might be gained that would be unobtainable in any other fashion, without having highly placed human agents available.
Micro-PK, even if limited to affecting electrical signals or the operation of computerized devices, is becoming more and more effective as military weapons systems become 'smarter'. A steam driven battleship of 1900, with mechanical systems to aim and fire its cannons, would be much less vulnerable to Micro-PK than a modern fighter aircraft which depends on complex computer controlled avionics systems to even maintain stable flight, let alone operate its radars, aim its weapons, communicate with the flight controller directing the pilot towards his target, etc.
It is interesting to note that the research at PEAR has indicated that Micro-PK seems to occur most frequently in systems that are unstable, right on the edge of probability, so to speak; liable to flip into one state or another with very little urging. This would describe a lot of military weapons systems, since they are normally operating under a great deal of environmental stress; temperature, vibration, G-forces, exposure to EMP, etc.