SketchPad is a web-based drawing program implemented only with HTML5 and JavaScript.
Galactic Plunder, made with JavaScript and HTML5 Canvas, shows that shooting games can be built without Flash.
HTML5 supports watching videos without installing Flash or plugins. In addition, viewers can interact with the video, such as this website allowing them to break each pixel of the video being played.
HTML5 Rocks provides slides for visitors to explore the special capabilities of HTML5, such as using the keyboard keys to switch slides, change the background .
Enter any site and the collaboration site between Arcade Fire and Google Chrome will demonstrate the ability to play videos without installing software.
Another interesting experience with HTML5 is Browser Ball - allowing users to open multiple windows and move objects (balls) between them.
Hakim page introduces some games to prove what users can do with HTML5.