I used MobileOrg for a while but couldn't figure out a seamless workflow to eliminate manually pushing and pulling on the desktop. Automatic HTML export to dropbox works fine for mobile viewing, though.

How do you do the indexing part?

Is it possible to record audio with org-mode (and then categorize/annotate)? And do quick drawings with a stylus on the screen?

> Is it possible to record audio with org-mode (and then categorize/annotate)?

I haven't seen any plugin to do audio recording from Emacs, but it should be easy (if you're willing to dig into elisp a bit; it's not hard) to invoke any kind of CLI tool for that, and then a/ move the output recording to a proper place, and b/ capture the link for org-mode.

> And do quick drawings with a stylus on the screen?

There are picture-mode and artist-mode in Emacs for that, but I haven't tested any of them with a stylus and a touchscreen, and draw in text mode.

Images and video?

Sure, Emacs can display images inline if you want it to, or just open it in another buffer ("tab") or with an external application. You just store the image in a separate file and make a link in your org-mode text file.

As for videos, I don't recall Emacs being able to play them directly, but you can easily invoke an external player.

images are important, that's how I learn countries (point on map) and birds