An interesting exercise would be to try to imagine a society of humans whose minds operated the way most intellectuals today imagine human minds operate.
For instance, see the recent post by LukeProg on values being relative. What would people be like if they really did have states as terminal values, the way folk psychology says they do?
Another exercise is: What would society be like if everyone knew how their minds operated? How would we act if people didn't believe in free will? (Asking that question gives me a headache... it seems to imply that we have free will.) How would we act if we were rational utility-maximizers?
One of the most important points raised by the sequences is that not all minds are like humans. In quite a few places, people have discussed minds with slight changes from human minds, which seem altogether different. However, a lot of this discussion has been related to AI, as opposed to minds created by evolution. I'm trying to think of ways that minds which evolved, and are effective enough to start a civilization, could differ from humans'.
Three Worlds Collide would seem like an excellent starting point, but isn't actually very useful. As far as I recall, the Babyeaters might have learned their baby eating habits as a result of societal pressure. The main difference in their society seemed to be the assumption that people who disagreed with you were simply mistaken: this contrasts to humans' tendency to form rival groups, and assume everyone in the rival groups is evil. The Super-Happies had self modified, and so don't provide an example of an evolved mind.
So here are my ideas so far.