Where to capture function availability?

I have always been tempted to build a site map that shows what the user can do from said page. For instance, a site map that shows a “My Account” page with ‘manage account’ as a function on that page and all the CRUD functions as available off of ‘manage account’

But this doesnt, and wont work.

What types of diagrams do you use to capture this kind of information? I can do an activity diagram for each of the functions, and I guess I could use swimmers lanes for the pages and menu items, but this would quickly get complicated.

Is there a better way? Im sure there is.