The module docs are probably the most important page in the ansible documentation, and I have yet to document all the new shiny features available in 0.6 (particularly the database modules), though this is coming.
Anyway, I've cleaned them up quite a bit:
http://ansible.github.com/modules.html
One thing to note -- I'm standardizing on "absent" and "present" and "name" versus various aliases that were accepted (and still be), just to keep things simple. If in some event there is still a module that doesn't accept "name" for it's "primary key" of sorts, let me know, and we'll fix it. Ditto absent/present. Think everything works that way though.
Where I have something wrong in the above, please let me know. Easiest way to do so is to send me a pull request to the "rst/" files in the ansible/ansible.github.com project.
--Michael