Regardless of how fantastic of a developer you are, there are very few people who manage to memorize every element of their specialty. Even if you do fit into that elite group, what about other languages and technologies where you have some knowledge, but don't always remember it?
Have you ever visited OverAPI.com? This website is filled with cheat sheets and references that you can use while working on any technology job. For example, you can get a Python Cheat Sheet, jQuery Cheat Sheet, Ruby Cheat Sheet, PHP Cheat Sheet, Regex Cheat Sheet and many, many more!
Do you have any resources you like to use for quick reference guides?