Letter writing. So much of history is based on personal correspondence that has survived... where will the archive our people chatting online be found in the ages.
Also, history in genral...electronic media is not sure storage at all.
-Ed
A lot of online correspondence is archived, both chatting programs and email. In fact, when email started coming around, many historians thought it would be a great thing, as the telephone left far less records of what people talked about from the 1930s to early 1990s than the previous era before it.
There's also something to be said for virtually everyone owning their own printer. Of course, how much of this material is actually saved is another question entirely.
One thing the internet hasn't killed is the belief in really stupid theories. If anything, it's just given them a stronger base.