The app looks inside your Evernote notes (Evernotes?) for checkboxes, and extracts those items on their own. Then it re-arranges and re-displays them in a very smart, Moleskine-style notebook format.
What I like about this idea is that the todo items retain their context inside Evernote. You can keep a short list of todos with the other notes and info that relate to them – then, when you simply want to see the todo list as a whole to see what you should do next, Egretlist gives you that at-a-glance overview.
The Evernote team are impressed as well, and they’ve published an interview with the Egretlist developer that explains the thinking behind it in more detail.