I've found that forums seem to provide much of the knowledge previously transferred through Geocities. Detailed, human, non-encyclopedified information about almost anything is available spread through a vast quantity of subject-specific forums across the Internet rather than across webrings hosted on Geocities and the ilk.
I think part of the reason for the shift is that forums have gotten much more advanced: most include a personal homepage, photo gallery, and provisions for making "uber/FAQ" threads that easily surpass the most meticulously curated Geocities sites.
The problem is that forums aren't the ideal medium for collecting knowledge: how many times something you're looking for is buried in a 500 page topic, between non relevant, troll or deleted posts.
And for some reason every forum I've used has a useless search function: Yes, it searches, but it doesn't find or list results in a convenient way for someone who's looking for something specific.
I think part of the reason for the shift is that forums have gotten much more advanced: most include a personal homepage, photo gallery, and provisions for making "uber/FAQ" threads that easily surpass the most meticulously curated Geocities sites.