[Flutterbyes]

This is something I bumped into while perusing the Google Play.

It's an Android app called Oekaki Supple. It's primarily in Japanese, and only the first few notes have been translated into English so far.
https://play.google.com/store/apps/details?id=jp.gr.java_conf.natnag.es100

You can also see these notes and more in Japanese on Pixiv
http://www.pixiv.net/member_illust.php?id=642630&tag=OEKAKISUPPLE

It's a set of anatomy pointers for artists, many of which specifically address common areas of confusion and flubs that I've seen even more experienced artists make.

(I did a bit of looking and I'm pretty sure this hasn't been posted here yet)