CMS preferences are customisable across sites (if you run multiple sites off the same installation), and for each level of user. Here is a list of the built-in preferences and what they do:

blog.allowcomments (default: false)

Whether blog comments can be made at all. If set to false, blog.comments.default has no effect.

blog.atomposts (15)

How many posts to display in an atom feed of the blog.

blog.comments.default (20160)

How long (in minutes) that commenting is available, from the posted time of the blog post. Set to 2 for indefinite availability.

blog.edit (false)

The user can make or edit blog posts.

blog.main.collapseposts (false)

Truncate long blog posts where more than one is shown.

blog.showauthor (false)

Each blog post shows the author of the post, and links to all posts by that author.

calendar.edit (true)

The user can make or edit events on the calendar.

cms.edit (true)

The user can make or edit the content of pages on the website.

filemanager (true)

The user has access to the file manager, and can upload or remove files.

gallery.edit (true)

The user can create or remove galleries, and edit them.

gallery.folders.displaymode (0)

How a gallery should link to subgalleries. Current values are 0 (not at all) and 1 (with a folder icon among the images).

gallery.image.maxheight (500)

The maximum height of images in galleries. Uploaded images are reduced to this size at the point of upload.

gallery.image.maxwidth (800)

See above.

navitool (true)

The user has access to the navigation tool, which can edit the website's navigation section.

user.changepassword (true)

The user can change their own password.

users.admin (false)

The user can add or remove other users, or change preferences.