Even if HTML5 is not standard yet, I am sure you are aware that nearly all the browsers already support most of the html5 features. If you haven’t play with html5 yet I think now is a good time, considering that there are plenty of mature learning resources out there. Bipin Joshi in developer.com points the top 5 in his opinion. Briefly are those below:
- Audio and video elements
- Canvas element
- New input types
- New form features
- Custom data attributes
Have a read in this link.