Awesome site that allows you to code a little snippet and see if it works, as well as share with others. The coolest part is that you can include a bunch of the more commonly used libraries, such as JQuery, Dojo, ExtJS/Sencha, Underscore, and Raphael (plus a TON more, but I thought I’d throw out the big ones/my favorites). You can even get a plugin or two for your IDE or text editor to throw it directly up there when having issues.
Well, that’s about it. I just thought I’d share some resources for the beginners out there.