I have heard of many people who have memories of past lives, especially in Buddhism. There are many monks/teachers/Masters who are able to do that. There are stories that I would rather not mention here.
In my IRC channel and in this forum alone, there are 2 people who were Tibetan Lamas in previous lives (they are not monks currently... just lay practitioners)... both of them has reached certain level of realisations. (One of them is Longchen in this forum). The other has never posted in this forum before. Other than these two who visits my channel and this forum, I believe there are others who visits my channel who may have certain memories but have not mentioned about it.
If you meditate deeply enough... you may be able to recall your previous lives especially in Samadhi. It is something that we can see for ourselves if we put an effort in our practise.
Plenty of people who have gone to meditation retreats, for days or a week, have received memories of previous lives. Think about it: these people went for a week retreat, how about monks and nuns who practise hard... often meditates throughout their life?

This is from the other guy.. not longchen -
This chat conversation was recorded more than a year ago. He comes to the IRC channel sometimes. Some of us have met him before. His nickname as been replaced with
A to protect his privacy. He has recalled many many lifetimes... even in many different realms of existences in the past.
[18:43] if i can - hopefully this would be my last incarnation .
[18:43] since i know who i have been ....at least some of it.
When asked why he has not wanted to teach again, he replied...
[18:50] because karma is also by association.
[18:50] by wishing that i come back to teach - i become caught again in a certain mind stream.
[18:51] even by telling you what i know - I have allowed you to enter my mind stream .
[18:51] thus we may share experiences together.
[18:52] that too is because of previous lifetimes ..and also karmic forces .
[18:52] unless we are so mindful of being beyond the river of the mind- it may sweep us unaware.
[18:53] this is my explanation of why people kill others in a heat of passion even though it is over a small thing and the person is a stranger.
[18:53] because of this , its all phenomenon.
[18:53] so one who practices mindfulness can eliminate karmas quickly .
He later mentions about the karma...
[19:01] do the cells in ur body belong to u???
[19:01] The true essence - You are the Divine.
[19:01] all things are you.
[19:02] when you hurt someone- you hurt yourself, that is why karma always exists.
[19:02] in all states of matter and intention .
[19:02] The mind is merely a tool .
[19:02] and an extension of the Supreme Reality .