Mailing list wiki combo?
I've written before about the dichotomies between serial and browseable, between writer-friendly and reader-friendly.
One idea that now seems obvious is to integrate wiki functions into a mailing list manager (particularly one that does a web interface to the mailng list.)
In particular, one should be able to "cc" a message to sections of the wiki and have it added. For example, to an FAQ section. In addition, readers of a message should be able to promote it into sections of the wiki either by clicking links in the HTML version of the message, or by forwarding the message back to some magic addresses at the mailing list manager.
Thus when sombody on a mailing list makes a useful answer to a question, it could go quickly into a wiki style knowledge base, for easier browsing and searching. Many mailing lists today allow you to search the list archives, but unless you know your vocabulary, you may not find the answer to problems you are trying to solve, even though they exist there.