display: tree may be used to mix styled element views and non-styled (tree-like) element views. This is particularly useful for meta-information (such as DocBook's bookinfo, sectioninfo, indexterm, etc) for which a sensible style is hard to come up with.
Example (DocBook):
display: inline-block may be used to specify a rectangular block that participates in an inline formatting context. (This is similar to inline-table.)