Contribute to READMEs (opens in new tab)

I was more intrigued by the article linked in the second paragraph: Readme Driven Development (http://tom.preston-werner.com/2010/08/23/readme-driven-devel...)

This is close to what I do (and encourage my team to do). I usually start by writing a commented code snippet demonstrating proper usage of the class/function I'm about to implement.

Fixing typos or improving documentation is another super easy way to contribute. You could probably find many typos in many repos you use, especially in code samples.