I like it. I really love the minimalist styling. I think it'd be cool to add keyboard navigation so that you can select items and complete them. (Arrow up/down to select item, shift+alt+d{space, enter...} to mark as done?)
Oh, and I see that checking something as done prepends that line with "X ". So if I start a line that way it begins as done. Admittedly I was intentionally trying to cause this to happen, but maybe it'd be possible to flag the lines in some other way than with the "X "?
