What I believe;
Crop Circles - Usually very large and done 'overnight'. I doubt that, the people who find them, usually make them over a period of time, and act suprised when it's finished

. A complete hoax to attract attention.
Photo Orb-thing - I have no idea, there isnt a photo of me without one.. might be a lens flare, only its all the time.. :S
Colder Areas - I believe that the person 'believes' the place is colder than it actually is. Say they are out hunting 'ghosts'. They will automatically believe there are ghosts around, and therefore make themselves think the area is colder.
Spirits/Ghosts - I have actually seen one. However, I do think that it MAY have been an illusion, I had just woken up in the middle of the night, my window was open, and I saw a cyan/white mist come through my door.