Cheat sheets are nothing but collection of notes for future reference and it is inevitable for programmers as they have work on multiple languages these days. But cheat sheets are spread all over the internet and there is no where to refer them at one place until recently. OverAPI now offers a largest collection of cheat sheets at one place for the most popular programming languages and libraries.
OverAPI also has a chrome extension which is very handy for developers to make a quick reference. Contributions are welcome from anyone via pull request on github which is awesome. Though these cheat sheets are primarily aimed at programmers, there are some non-developers cheat sheets are in there as well.