The beauty of HN is that this is pretty much the only place where you can meet the person with exactly the same exotic nerdy problem. I am thinking about moving from TiddlyWiki on Dropbox to Simplenote that (IIRC, at least when you pay) can synchronize notes to Dropbox, has a native iPhone app and a whole roster of 3rd party clients for other mobile OSs and desktop clients (http://simplenote.com/downloads/).
I was exactly the same TW/dropbox until a couple months ago...
I'm almost finished polishing up an App I wrote for personal use that edits/ synchs a folder of .txt files. (Maybe this weekend I'll get around to finishing it?)
Its not groundbreaking but it'll be available iOS and Android - then use your favourite text editor on pc/mac.
Email me if you want to beta test in a week or two?
I use PlainText on iOS and Notational Velocity on OS X. NV supports a [[link]] style of linking between pages. Sync as txt files into a subfolder on Dropbox.
Unfortunately, it looks like PlainText doesn't support those links.
