Oh yeah, this talk of a notes app reminded me.
I was looking for an outliner/ note app recently and saw
ThinkBook. I bought it for 2 bucks and I think it's great
http://itunes.apple.com/ca/app/thinkbook-write-plan-outline/id421926271?mt=8
it's from the same dude who wrote comic zeal.
it's very easy to enter notes and choose from plain or checkmark notes. adding indents is simple with a gesture on the line you're writing on.
but what really makes it work well for outlining is the "slider" UI element that sits on the right fo the page. you can push notes into this slider where they are stored and then you can pull them out in a different section of your notes. think of it as super fast cut and paste to reorganize note structure. very handy for this type of app and i have not seen it elsewhere.
there are also some advanced features like search folders if you have a bunch of data that you update frequently across multiple notebooks and need to be able to view quickly
anyway, it's only a couple bucks and is, imo, well worth it. great attention to detail.