There are lots of different pieces of equipment needed to do a successful paranormal investigation. Below are the pieces I use when I go out with Northampton Spiritseekers.
Digital Camcorder with night vision. Great for doing night vigils and recording Orbs etc...
Digital SLR Camera. The best camera to get those spooky photo's, also by using this type of camera, you have less chance of capturing 'dust' Orbs.
Two-way Radio's or Walkie-Talkie. Great for when doing large investigatons and your team splits up in to groups. Can use to keep in contact and check for position when noises etc... are heard.
Digital Voice Recorder - EVP. Best used when doing investigations, trying to capture sounds from the world of spirit.
L.E.D Torch. An essential piece of equipment for any paranormal investigation. Much brighter than normal bulbs.
Electro Magnetic Field Meter - E.M.F. Spirit's are said to give off an EMF reading when close by.
Pen and Paper. The basic needs of any investigation. Used to make notes, write down things that happen and base line results.
Crystal Pendulums. Used to answer questions when contacting spirits. Can only give a yes/no answer though. Can also be used as a lock-off experiment during vigils, to see if they move on their own.
Crystals. Used for healing and other purposes. Each crystal/stone has it's own meaning and power. Good for using during investigations, as some stones are said to help with contacting spirit's through mediumship and psychic means.
Dowsing Rods. Used for communicating with spirit's. Can only answer yes/no questions though, like the pendulums.
Tripod. Used to steady camera when taking photo's. Can also be used with a camcorder when filming or for locked-off vigil.
Temperature Thermometre. With air temperature probe, better than the laser thermometre's because they only give reading on the point that the laser is in contact with.
Metal Briefcase/Storage case. Used to store all your ghost hunting equipment. Looks great and is waterproof.