One of the problems I've recently run into with WordPress is putting featured images on my RSS feed and then getting them to show up on RSS readers.
Basically, the problem would be solved if the
<image> tags were attached to featured images by default in the RSS feeds for categories, tags, and of course the main feed.
I suggest adding it to the Reading area. Here's a (very poorly designed) mockup of what I mean:
The solution I've coded into my functions.php does work on most RSS feed readers, but many users would find it easier and better to have a built-in solution. This feature would especially be useful for building mobile apps.