Ever stored rendering component data source items under a page? For example:
/sitecore/content/Page
/sitecore/content/Page/Datasources/ComponentDataSourceItem
It's a good practice and it seems to work quite well for page specific components.
But have you ever wished branch templates understood that in a logical fashion? What if this:
/sitecore/templates/branches/Foo/$name
/sitecore/templates/branches/Foo/$name/Datasources/ComponentDataSourceItem
...expanded out to have the branch create the hierarchy and re-link the layout details on the instiantiated branch item to point to the right child data source item?
Doing this lets you use branch templates to create preset rendering hierarchies, including page specific data source items.
Sound good? Well you've found the right place to get the code to do just that. This requires Sitecore 8 or above with the pipeline-based item provider to operate.