Designers and developers often like to use cheat sheets (a concise set of notes used for quick reference) as a quick way of looking up a method or a function and seeing how to use it and/or looking at what is does. We've used these quite a bit and they can come in very handy so here's a collection of some of the ones we have bookmarked:
12 HTML Cheat Sheets
12 CSS Cheat Sheets
You may also want to have a look through cheat-sheets.org as they have a good selection of sheets for a wide selection of languages.