Just wanted to list different ways to express your product backlog:

Mind map: in http://epistemologic.com/2007/04/08/requirements-management-user-stories-mind-maps-and-story-trees/

Effect mapping: http://gojko.net/2011/09/23/effect-mapping-in-practice/

(Mind map starting from Who, Why, What, How)

User story mapping: http://www.slideshare.net/nashjain/user-story-mapping

(Visual map with timeline and priorities)

Tree map: http://en.wikipedia.org/wiki/Treemapping

(You have to see it to understand – I can’t really explain… more useful for visual reporting)

Release driven user story mapping: here

Idea wheel: I need to find out what it is.

I will add some more in this blog soon!