Learning much javascript from one line of code

Since javascript is everywhere nowadays, it is really easy to learn new stuff everyday. Once you know the basics of the language, you can take bits of code from here and there that have a lot of knowledge in them. Bookmarklets are perfect examples of a bunch of packed functionality, whenever I discover a useful one, I enjoy studying their source, discovering how it can do so much. Also snippets to use external services, like the google analytics code, or facebook likebox, can teach us more than some books.