Custom Actions / Single Page Forms on a Site Page

I would like to be able to make customised pages that aren't directly tied to a list or library. I can do some trickery around this by make a list and creating a page that doesn't do any save part to display on a page. The form engine is already flexible, and formatting/validation/actions sets would be good to be able to insert directly onto a Site Page even if it was in the context of a complete form.

An example use case of this would be having a site page that may serve as a menu and some of these menu items perform actions ore have conditional formatting on them based on javascript calls. This action might be perform actions based on input into the page (a drop down for example).