StumblingOn sends you a random page from their directory.
The Tildeverse is a collection of publicly accessible computer systems, whose users typically publish their own web (and non-web) sites, and have community-building features like chat rooms and forums.
A Webring is a way to connect pages that are related in some way. They usually require the page to put a section that will link to other pages in the ring.
Web directories are curated listings of websites, often categorised.
Link pages are personal lists of websites on people's homepages.