How to submit a form when the return key is pressed?

To submit the form when the enter key is pressed create a javascript function along these lines.

function checkSubmit(e) {
   if(e && e.keyCode == 13) {
      document.forms[0].submit();
   }
}

Then add the event to whatever scope you need eg on the div tag:

<div onKeyPress="return checkSubmit(event)"/>

This is also the default behaviour of Internet Explorer 7 anyway though (probably earlier versions as well).