For one of my classes, I've been reading about The Well, and other early online communities (yes - it's very cool that I get paid - a little - to study this stuff). It is incredible to me that many of the archives of this and similar communities still exist. You can see, for example, Linus Torvald's first post proposing Linux. We can view and replay significant moments in incredible detail.
And most incredibly, we can do this with the benefit of hindsight. "Everything" is saved, so conversations (like Linus's) that seemed unimportant at the time, are still around, and can be analyzed in the context of their realized importance.
This memory of the web does have some downsides, however. One of the striking things about The Well is just how open and passionate people are, and that passion built a vibrant community. Before posting to the Web, I find myself self-censoring, because the medium can be so unforgiving, and I don't engage as fully as I think I would if the Web forgot.