The overkill of having to capture and test every keystroke for the ENTER key really bugs me, so my solution relies on the following browser behavior: 
Pressing ENTER will trigger a click event on the submit button (tested in IE11, Chrome 38, FF 31) **
(ref: http://mattsnider.com/how-forms-submit-when-pressing-enter/ )
So my solution is to remove the standard submit button (i.e. <input type="submit">) so that the above behavior fails because there's no submit button to magically click when ENTER is pressed. Instead, I use a jQuery click handler on a regular button to submit the form via jQuery's .submit() method. 
<form id="myform" method="post">
  <input name="fav_color" type="text">
  <input name="fav_color_2" type="text">
<button type="button" id="form-button-submit">DO IT!</button>
</form>
<script>
 $('#form-button-submit').click(function(){
    $('#myform').submit();
  });
</script>
Demo: http://codepen.io/anon/pen/fxeyv?editors=101
** this behavior is not applicable if the form has only 1 input field and that field is a 'text' input; in this case the form will be submitted upon ENTER key even if no submit button is present in the HTML markup (e.g. a search field). This has been standard browser behavior since the 90s.