Here's a wacky idea - arbitrary attributes that can be assigned on an individual node basis.
Even wackier - a brokerage system to allow these attributes to be globally registered.
What do I mean, and what's the point?
Right now, developers do all sorts of strange things to coax desired behaviour out of Drupal. Consider the case of featured content. You want certain types of content to be "featured", and you want to perform certain types of actions for featured content that you don't want to perform for other content. Perhaps a
graphic next to the title in a teaser view.
There are countless ways that a scenario like this gets tackled, three in particular which are most common. I don't think any of them are adequate.