My six year old remembers EVERYTHING from the time she was one up to now. She can't tell you what she had for lunch yesterday at school but she can tell you something that happened back when she was just learning to walk, in full detail. Things we haven't really told her about.
She can describe the house we lived in from the time she was 18 months until she was almost three. We haven't been back to that house since we moved, nor do we have pictures of it anywhere.
She will out of the blue come up with something, a true event that happened, that is never mentioned, and tell us about it. Like her third birthday party, which I've forgotten most details of myself, she'll talk about. She'll remember what she has been for Halloween every year since she was born (the first two halloweens' she's asked about her costume, but after that, she knows)
DH can't remember anything before turning 8. No specific childhood memories or anything. I can only remember things I've heard stories about or seen pictures of, so it's surprising to me that she can tell so many stories and give so much specific detail about things she shouldn't know a lot about. Her sister isn't the same way, she'll remember a few things that happened last year or the year before, but not a lot (she's turning 5 next month).
DD has been called a "genius" by every teacher she's ever had, and is advanced for her class, but I guess she has one of those excellent memories as well.
ETA: She also makes up far fetched stories, her imagination is fantastic. Every story begins with "when i was a little baby, you took me to the moon" or "when i was 3 and sister was 2, we went to china". Things that have never happened (especially the moon part lol).