Two ideas here:
The first one can be an app similar to Yahoo finance, where you can track stocks and at the click of a button, be able to share one of more of them on Steemit in a blog post while allowing yourself to comment on what you think is happening and what you think will happen. This could be a great way to get community insight into how the stock market (for those who invest in it) is doing/going.
The second idea here is not an app, but more of a functionality for Steemit (I don't know where else to post this). But the idea is that similar to YouTube, you can organize your blog posts into categories/playlists to help keep things organized.