identify sections in an xhtml document

Not sure if this is the right place to ask (as it could easily be a PhD research
topic) but maybe someone can sugest a good approach/reading, even better some
xslt code to do this...
Im trying to identify a maximum of 10 logical sections of an arbitary web/xhtml
document and add a name-anchor at the beginning of each section.
What I mean by section is things like navigation-menus, blocks of text/image
content, groups of links and similar.
For example, http://xmlsoft.org/ has four distinct sections:
1. Heading + Images,
2. Main Menu
3. Related Links
4. main content (could also be subdivided into further 3 text and 3 link/list
sections)
I would like a stylesheet to identify those sections and add <a name="$id"/> at
the beginning of each, leaving everything else intact.

Any input welcome

Dean