For a straightforward review of research in this area, including experiments with *remote viewing* under controlled conditions, I suggest the following publication:
"Margins of Reality" by Jahn & Dunne
Published by the Princeton Engineering Anomalies Research team. You may also wish to view their scientific papers, available for viewing here:
http://www.princeton.edu/~pear/publist.html
Should you find any problems with their scientific protocol, then by all means continue in this thread. On the other hand, if you do not wish your world view to be challenged by even this small quantity of evidence, then don't read it.
But please, do not make comments like "there is not a shred of evidence", "there has been no scientifically validated..." (maybe not you, but others on this thread).
It's good that you make reference to Carl Sagan's work, he is well respected, but a rationalist nonetheless. And as has been said, an explanation for a phenomena is not a proof of a mechamism, and many scientific protocols are too crude to be able to detect the kind subtle/quantum effects which would likely form part of any theory of ESP and the like.
Evidence exists, explanations vary, but condemnation appears almost ubiquitous - your comment about the easter bunny is a good example of the attitude of most of the raionalists - "we know it cannot exist, therefore we refuse to consider it". And sadly, this is most often the case, which might explain why funding for research into "psi" phenomena is so hard to come by. And worse, any scientist daring to perform such research is often ridiculed or even thrown out of their university. Very rational approach....
This is not really surprising, considering the antics of people like Geller, who gives the strong impression of actually being mad, but there is a sufficient body of work in existence to justify a more tolerant and inquisitive attitude, as well as further serious research.
One ofthe problems with biological/psychological systems, is the difficulty in obtaining statistically significant results, due to their complex nature and the myriad factors that come into play (such as how much sleep, what they ate, the time of year/month, what someone said etc. etc.). This is also true of many models of animal behaviour, and ecosystems. They are very difficult to study in isolation. However, some of the *psi* research has produced results of a significance only previously seen in physical experiments (the *hardest* of sciences), probabilites of the order of p=0.001 or less (p=0.05 is significant). But, even the best of experiments and strongest of results will not win the argument against a mind that refuses to change. "Never underestimate the power of denial".