Something you might find on InternetRelayChat (IRC) or on
MultiUserSharedHallucination games (MUSHes -- multi user text-oriented
roleplaying games) are '''lectures'''.

Somebody will announce a lecture on some topic, and then people can
join the channel or enter the room where the lecture is held.  One
person talks, the others ask questions and comment.

Benefits:

* Interactive
* Direct talk, less lag than via MailingList""s, UseNet or wiki page editing
* Demand-driven: people ask questions and direct the talk
* Automatically generates short messages and pragmatic explanations
* Easy to include examples from all over the web
* International, not limited by physical distance

Drawbacks:

* Little theoretic background
* Logs are hard to read; transforming the logs into a reference text is hard work
* With lots of active people, lots of noise and sidetracking (but many online communites have strong traditions in this respect)

Examples:

* http://www.linuks.mine.nu/irc/ by Gürkan Sengün

CategoryChat

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The idea of lectures also develops in BBS systems. Lecture topics are gathered and get priorities. Referents are assigned. The lecture is posted and discussed. In one case I know the lectures are refined and published in an associated wiki. -- HelmutLeitner
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