This is the 'genre' of the paranormal I believe in the most and I believe it would explain most paranormal incidents.
Here is my personal take on residual hauntings...
Firstly they can be positive or negative
The basic idea is that when an event of high emotional energy takes place, it can become embedded/absorbed into items or places.
So... if a psycopath broke into your house and you were running away from him in utter terror only to be cornered and stabbed repeatedly, the memory, the emotions captured at the moment of your death might be imprinted into that exact location or a more general imprint on the entire house. The emotions of fear, sadness and the cold of death might be experienced by people in that location long after your death. And the images or shadows of a man chasing a woman and then stabbing her, or a woman cowering in a corner, might be seen to play out repeatedly like a record stuck on repeat.
The same thing could happen at the happiest moments of your life - childhood memories of playing hide and seek, memories of being with a loving mother, or returning home after being away for a long time.
Many people have experienced cold spots only to be overcome by emotions of happiness, and the overwhelming urge to cry. I read one story about an old woman who kept seeing her son walking up her path with a newspaper over his head against the rain just like he did the day he returned home from veitnam in the rain hoping to suprise her.
It would also explain the images and sounds of children running around homes, giggling, playing games or singing nursery ryhmes or even interactng with a mother figure.
I believe the stronger the emotions left behind the more complete the 'image' would be - the more sentient the 'ghost' would appear.
This obviously is a bad thing when it's that psycopath =P
Also the emotional energy of people in that location would feed these imprints, making them stronger - and adolecent girls are widely believed by paranormal experts, to give off the most emotional/ psycic energy, which is why alot of major hauntings centre around young women just starting puberty (take a look at many of the most famous poltergeist stories and often they centre around one)
The japanese strongly believe in residual hauntings - and this type of haunting is featured in The Grudge (original japanese version and the western remake) subject yourself to that movie (it's not that scary honestly) as it explains a great deal about the japanese culture's stance on residual hauntings - They believe that if a person dies in a moment of high emotion, that those emotions, that moment can be imprinted into a house as a spirit of revenge/rath, and that anyone entering that house will then fall subject to its curse.
I have lived in a house where a vicar commited suicide though I was not told by my family until we had moved out. My Dad who was a vicar while we lived at that house suffered greatly from depression and had many suicide attempts over the years. Whether he would have done them if we lived in any other location is open to much debate and sceptisism but my mother and grandmother both felt a strong depressive and dark 'pressence' when they first went to that house. Whether it is the events that occurred there with my faimly or not that house definatly has a dark feeling about it to me...
It would be really interesting to see if the emotional events my family went through in that house and others have left any lingering impressions.
Anyway this is just my opinon and you're quite welcome to rip into it you wonderful sceptics hehe =P