Sometimes there is data all over the confluence space that you want to bring together on one page.
There are currently some crude methods of acheiving this by using excerpts or page includes, however it would be much nicer if you could arbitarily define metadata in your pages: (ok, I know we're creaping towards RDF here...)

For example:
Page theory1:

{exceprt}blah blah{exceprt} {metadata:abstract}

The article abstart

{metadata:abstract} {metadata:details}

Details

{metadata:details}

Then in my bring it all together page I can:

{include-metadata:theory1|abstract} {include-metadata:theory2|abstract}

etc...