The site includes:
- Thimble is an online HTML editor you can use to create web pages. It is a simple split pane with your HTML code on the left and the resulting output on the right. You can publish the page to the Webmaker site so it can share it with others. The site includes a number of projects designed to get your started learning.
- X-Ray Goggles is a tool for exploring the code on a web page.
- Popcorn is a tool for creating Video
The Register has a detailed review here.