Outline+ is compatible with OneNote. It can sync notebooks stored in Dropbox. It's a bit pricey, though.

I have an Ipad3 and an iTouch. I've found that synchronizing data between 2 devices on Dropbox (and originally in iCloud) to be pretty flaky. On a single device, I think it may be a nice experience....

Take a peek at ProjectBook. It can create notes with outlines. It can also import doc, dock, pdf files and has a todo manager. The notes can have ink annotations. I use PB on an iPad3. Not sure h...

Try ContactsXL

I tried pasting in an indented text file and all it would accept is the first line. I'd need to see some sort of import capability before buying it. TreeSheets manages this wonderfully.

You might take a look at TaskMerlin. Version has a highly customizable tree, as well as a calendar that will show tree items with dates/times.

I own both a PC and Mac. I bought Crossover for the Mac, which sets up a virtual Windows environment. Both Treesheets and Ecco run quite well in the system. So does Action Outline, although I don'...