Blog entry - all users are permitted to have their own blog
Book page - all users are allowed to add a page to an existing book, e.g. the site guide. They can't edit other people's pages without additional permissions.
Forum topic - can contribute to any forum they can access
Image - See page
News item - not sure about reasonable restrictions
Page - can create pages (with images- see above) and edit their own pages. I think this is sufficient for volunteers to maintain whole subtrees of the site on specific subjects. They will need some help to get their topic properly linked up from known pages and may need some other support occasionally.
Left menu items
Needs organizing just like those of more permitted users - mostly deletions of junk
