I find this a fascinating idea:
(quote)
The intermediate state, or bardo, is so called because it is the state between death and the next rebirth. Beings who wander in this state are known as `bardo beings’. The easiest way to gain conviction of the existence of the bardo is by considering the analogy of the dream state, which closely resembles the bardo. Both the dream body and the bardo body arise in dependence upon subtle energy winds. Both lack flesh, bones, blood, and inner organs, but both have complete sense powers. Just as the dream body develops from the clear light of sleep, so the bardo body develops from the clear light of death; and just as the dream body is known only to the dreamer, so the bardo being is seen only by other bardo beings and not by ordinary beings who do not have eye clairvoyance. The location of the dream body quickly shifts and changes, and acquaintances made in our dream are fleeting. Similarly, the location of the bardo being easily shifts and changes, and acquaintances made in the bardo are short-lived.
As we fall asleep the gross winds gather into our heart and we experience the same signs as the close internal signs of death, from the mirage-like appearance to the clear light. Yogis and some meditators who have developed their mindfulness can be aware of these signs as they fall asleep, but for most people these signs are not clearly perceived because we lack mindfulness during sleep. After the clear light of sleep we do not immediately wake up but we enter the dream state and develop a dream body. In a similar way, as we die, the gross winds gather into our heart and we perceive the internal signs of death. From the clear light of death we do not immediately reawaken into a new life but we enter the bardo and develop a dream-like bardo body.
Bardo beings have five characteristics: (1) they take the shape of their next rebirth - for example, if a human is going to take rebirth as a dog his bardo body will be the shape of a dog, and if a dog is going to take rebirth as a human its bardo body will be the shape of a human; (2) they arise instantaneously with fully formed limbs, sense powers, and so forth; (3) they have contaminated miracle powers - their bodies are not impeded by solid matter so they can, for example, travel through walls and mountains, and they possess contaminated clairvoyance; (4) their vision is not impeded by material things - they can see through physical objects such as houses, and they can see things at a great distance; (5) only bardo beings can perceive other bardo beings - ordinary humans, except some with limited powers of clairvoyance, are unable to see them. Immediately after our death we shall take the form of a bardo being with these five characteristics.
(unquote) source: death-and-dying.org/intermediate-state.htm
clairvoyance…anyone?
I was always amazed by the clarity and depth of those descriptions of the 3 bardos between death and rebirth! Those bardo beings are also mentioned I think… Apparently it sometimes happens that a bardo body starts dwelling because he/she is lost in the dimensions he/she is in. The bardo body then has the power to enter dreams of living people or to show themselves to people who have the gift of clairvoyance. Usually though, most bardo beings find their new place of rebirth within 49 days. It’s also amazing that the clearest moment to “become lucid” after death (thus, to become enlightened by realizing the illusionary nature of that state) is exactly at the moment of death. Afterwards it gets more and more difficult because more and more illusionary and sometimes fearful imagery tricks our egos. But theoretically it should be possible even to become enlightened to a certain level when you’ve already found your new place of rebirth. But that as a sidenote. And to answer your question, no I don’t think I’ve seen one yet, unless the dead relatives from my dreams were really them, trapped in the bardo dimension 
That’s just general knowledge about tibetan buddhism ( I’m also on a mailing list where it’s told about dzogchen.) So, as it seems to me that the link given above contained inaccurate information, I tried and completed my information with a quick search on tibetan buddhist sites.