[iheartmemcache]

I too prefer the human consumable format. If by 'media support' you mean embedding media, you can easily script image rendering for it (assuming you compiled with Xlibs or Cocoa support or whatever your platform uses- sadly the best cross-platform interface (QT) is LGPL which will never be upstreamed to GNU/Emacs) and on ELPA there's an extension for basically every audio player out there. I'm not sure what it's like on OS X, but writing a minor-mode to auto-parse file:///home/foo/bar/.avi|.mp4|*.mkv and generate a thumbnail and/or make a clickable URI should be trivial as well.

https://www.madoko.net/ I've been using this for ages, it's a superset of Markdown, pretty solid. It's really hard to beat (La|Te|Lua)TeX for certain things (I'd never write a dissertation or master's thesis on Word because even with all of the plug-ins it's absolutely abysmal for citation management (BibTex) and rendering even the most trivial of diff eqs) but this gives TeX a run for its money. It's a pretty decent option which seems like it might be up your alley. (Org-mode is probably what you're looking for though).