I'm currently working on another WordPress theme, supporting post formats. Adding post formats support to theme is easy, obviously — just few lines of code in functions.php. However from user's perspective it doesn't change anything. They still have the same form to fill. So I wonder how to replace the entire adding post form to something more relevant. For example: quote — it needs basically two fields: quote text and quote source... Link: it needs URL field, and maybe description, maybe title.
Take a look how Tumblr does it. It first asks you for post format and then displays appropriate form.
I'd love to avoid using external plugins and have it working out-of-the-box because I don't want to make my Clients install plugins to use theme I gave them.