Anyone know of a good checklist/to-do app for iPhone like this?

Things!!

edited: because i’m not sure this is actually what yr looking for. :-/

Have you looked at Remember the Milk?

Thank you, Justine and Bill. These apps are more project- and time-focused than what I need. ZeptoLiner Lite is closer to my ideal as it allows for a more general-purpose outline with checkboxes. But it doesn’t give any visual indication of how “done” each branch is when the branches are collapsed. If it could do that, it’d be close to perfect.

Actually, “perfect” would be an app equivalent to ListMaker on my old Palm TX. ListMaker is kind of like Things and ZeptoLiner rolled into a single app, and I have yet to find any one iPhone app that covers all of the same features. Sadly, it seems like Installigent—the company that developed ListMaker for Palm—is no more, else they may well have wanted to make an iOS version.

Is this the same ListMaker?

It doesn’t look like the same one, but it does look promising. I’ll have to check that out!