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.