It is not something like this what you looking for?
http://www.grafxsoftware.com/forum/10_734_0.html
You can go more deep, like menu_cat1.html, menu_cat2.html for example, we tried to cache with USE_CACHE, but that generate the whole page and is OK ONLY when you don't have dinamic data what change from time to time. For example if you have a login in the page, all is gone, cause then cache will be show to all with user login.
So use partial cache is like in that small example and if you need for each category a new page, then use menu_cat1.html, menu_cat2.html where the number is the category ID.
We use this in a site where when I'm in a category page, I show the category in different color and BOLD, so we need for each category a cached menuxx.html.
Hope this help.