I would like to see hierarchical (multi-layer) type drawing supported in OOo 
Drawing.  Similar to a data-flow-diagram concept, a hierarchical drawing would 
allow illustration of a system's overall layout on one page, then allow 
detailed illustration of sub-block internals on supporting pages (with a 
mechanism [double click, context menu, etc] for navigating from level to level 
in the drawing).

Ideally, the tool would automatically manage any links between the levels.  
For instance, if the top-level drawing shows two inputs and three outputs to a 
sub-block, creating the detail page for the sub-block would automatically 
incorporate matching ins/outs on the detail page.  
Additions/deletions/modifications to the ins/outs at either level should be 
propagated to the other associated drawings.

(Similar to MSVisio's DFD template, but without some of the Gane-Sarnson rules 
like no splitting data flows to more than one destination, etc.)