I just pushed change to explain.depesz.com that allows for processing and displaying hints for plans.
For example, take a look at this plan, and check if you'll notice subtle “HINTS" tab.
In there you will see example hints – one about sort and memory, and the other about missing index.
It is not much, but it's a step in (hopefully) right direction, when the explain tool will also provide, automatically, some ideas on what to do to make the thing faster.
Hope you'll find it useful.