- placeholder : display some (helpful) text as long as field is empty
- autofocus : when form is displayed, cell with autofocus is the 1st to be filled
- autocomplete : allow/disallow autocomplete in forms based on the previous input you made
- required : mark input field as required
- pattern : allow to define a regexp pattern against which the input will be validated
- list & datalist : it can be seen as an improved implementation of select/option
- multiple : allow to manage a 1-n sequence of field : ex you can have a form with 1 to n email field to invite people with n being dynamic.
- form : defied at a field level, will define to which form the field is related to
- formaction : specifies the file or application that will submit the form but defined at a <input type=submit> or <input type=image> level.
- formenctype : specifies how data will be encrypted but defined at a <input type=submit> or <input type=image> level.
- formmethod : specifies the method used (GET/POST/PUT/DELETE) but defined at a <input type=submit> or <input type=image> level.
- formtarget :specifies the target window for the form results
You can see some other attributes like on the HTML5 Form attributes from W3Schools ;
- novalidate, formnovalidate about input field validation,
- min/max or step to manage range of date / numbers
- height/width about input field size
If you add all this new with also the new input types attributes (email, image, date, range, etc), HTML5 forms are a significant improvement over forms we know today. The only limit so far is the implement of all these new standards in the modern browsers
[Edit 1] : Regarding the new attributes for input tpyes in form for HTML5, HTML5Doctor.com published a 2nd article after this one introducing these new attributes with an associated demo => HTML5 Form input types
[Edit 2] : Read also the "New guide to the new HTML5 form input types"