Not all attributes work in all browsers. And some do not work in any browser (March 2012)
A shortcut key to activate/focus an element
class: refers to the class in a style sheet an html element can have one or more class names
Specifies whether the content of an element is editable or not
true | false
This text is editable - TRY IT
Specifies a context menu for an element. The context menu appears when a user right-clicks on the element
dir Specifies the text direction for the content in an element. W3C lists this attribute as global but I can only get it to work within the bdo tag.
ltr Default. Left-to-right text direction
rtl Right-to-left text direction
<bdo dir="rtl">this he has a right-to-left text direction
draggable="true" or "false"
Specifies whether an element is draggable or not
IE introduced this attribute with IE5
the elements within the tags <a> and<img> are draggabe by default
dropzone="copy" or "move"
Specifies whether the dragged data is copied, moved, or linked, when dropped
The browers should not display a hidden element. This attribute can be used to hide an element until a specific condition has been met.
A unique id for an element
Each id is unique to that element within any given page
the language of the element's content
Specifies whether the element is to have its spelling and grammar checked or not