I first learned about this site via a post on The Chronicle of Higher Education’s ProfHacker blog. It’s pretty neato!
For starters, you can play around with existing projects by modifying the HTML (HyperText Mark-up Language, the basic language of the Web) on what Thimble calls its “hackable” sites.
For more of a challenge, you can start your own project and see it through to completion, right there in the Mozilla Thimble page editor. The nice thing about this process is that you see the code on one side of the screen and your creation (how it looks, or “what you see is what you get” [WYSIWYG]) on the other. Once you’re finished, you can publish your page so that it’s accessible via the thimble.webmaker.org URL. You can even copy the code you’ve created and paste it into your own site’s HTML editor. This would be especially handy if you don’t already have a WYSIWYG program like Dreamweaver or even WordPress.
Thimble’s motto is “Don’t just sit there — Make something!” If you do make something, I’d like to hear what you think about the process and maybe even highlight your webiste here.