Speaking personally, I feel like Usenet Newsgroups (quite a bit after the subject of this piece) were one of the peaks of "useful information density" on public networks. At least it was for me. Another was the heydey of RSS, when everyone published available feeds. Perhaps - if we are lucky - we are on the cusp of a third, with personal autonomous software agents[1] spidering out and retrieving dense information for us.
[1] "Boxed" for each user, instead of a gimmicked model that just feeds you crap.