Childrens Haunted Playground Swing
In Firmat, Argentina there is a playground that has three swings side by side. Locals say the swing moves independent from any visible external source for up to 10 days at a time!!

Locals are also convinced that a ghost is behind the, “Haunted” playground swing that moves backward and forward on its own. This started three to four months ago before local patrons called in the police. The police (I suppose as there was no one to arrest) were equally puzzled and subsequently called in physics professors.

The professors were unable to find an explanation, so after ruling out possibilities of magnetic and electrical fields, and wind currents the physics professors have called on, “Ghost Hunters!!”

Teacher Maria de Silva Agustina said that the playground was haunted, adding, "One child called it the Blair Witch Playground. We believe it is haunted." (Reported in the UK Sun tabloid)

I suggest you turn the sound down a little as original audio is very poor.

Source : http://www.ufo-blog.com/ufo-blog/2007/10/haunted-playground-swing-firmat.html