Some building blocks already available:
  
  http://jedmodes.sf.net/mode/filter-buffer/filter-buffer.sl
     Hide/Show lines based on regular expressions (uses pcre).
     
  http://jedmodes.sf.net/mode/folding-keypad-bindings/folding-keypad-bindings.sl
     Use the Number-Block keys for (un)folding and navigation.
* a fold mode based on underlined section headings (according to the
  reStructuredText syntax).
  
  This way you can have a custom structure with nice (and understandable
  to all) comments.
       
  http://jedmodes.sf.net/mode/rst/rst-outline.sl
     Outline/Folding using reStructuredText section headings as markers.