Wouldn't it be nice if life had a cheatsheet? This is a place to collect concise help for any given topic.

Create your own today, or contribute via GitHub. Here's what we have so far:

Title
Description
Author(s)
ECMAScript 6 Cheatsheet
Everything about the latest version of the ECMAScript (JavaScript) standard
Erik Moeller
Markdown Cheatsheet
Foundations and GitHub extensions on one page
Erik Moeller
R Reference Card
Free software for statistical computing
Tom Short
Matt Baggott