Finding the previous/next line at same indentation

[Micah R Ledbetter]

Ladies and gentlemen of the list,

I'm editing a file which describes a hierarchical relationship between  
objects, with children indented from parents.

Sometimes I want to find other children of the same parent, which will  
naturally be at the same level of indentation. Sometimes, there are a  
great deal of sub-children in the way, and navigating pages and pages  
of this can be tedious. Would someone point me toward some elisp code  
that helps me accomplish this?

As a bonus, it would be cool to intelligently encounter indentation  
which indicates a new entry - that is, instead of ALWAYS finding the  
next or previous item at the same level of indentation, if it  
encounters a line at a *lower* level of indentation, it should halt  
(or even wrap around to the beginning of the current entry).

Thanks in advance.

 - Micah