User-contributed content has been around for a long time, in the form of
Usenet Newsgroups. Newsgroups are still around.
A newsgroup devoted to taxes is
news:misc.taxes.moderated
You can search for key words using
http://groups.google.com/
A new method of collaboration is called a "Wiki", made famous by
WikiPedia
the user-created and edited online encyclopedia.
There is a Wiki devoted to taxes, created by Intuit, called taxalmanac.com
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