using href links inside <option> tag

Question

<select name="forma" onchange="location = this.value;">
 <option value="Home.php">Home</option>
 <option value="Contact.php">Contact</option>
 <option value="Sitemap.php">Sitemap</option>
</select>

UPDATE (Nov 2015): In this day and age if you want to have a drop menu there are plenty of arguably better ways to implement one. This answer is a direct answer to a direct question, but I don't advocate this method for public facing web sites.

UPDATE (May 2020): Someone asked in the comments why I wouldn't advocate this solution. I guess it's a question of semantics. I'd rather my users navigate using <a> and kept <select> for making form selections because HTML elements have semantic meeting and they have a purpose, anchors take you places, <select> are for picking things from lists.

Consider, if you are viewing a page with a non-traditional browser (a non graphical browser or screen reader or the page is accessed programmatically, or JavaScript is disabled) what then is the "meaning" or the "intent" of this <select> you have used for navigation? It is saying "please pick a page name" and not a lot else, certainly nothing about navigating. The easy response to this is well i know that my users will be using IE or whatever so shrug but this kinda misses the point of semantic importance.

Whereas a funky drop-down UI element made of suitable layout elements (and some js) containing some regular anchors still retains it intent even if the layout element is lost, "these are a bunch of links, select one and we will navigate there".

Here is an article on the misuse and abuse of <select>.

You cant use href tags within option tags. You will need javascript to do so.

<select name="formal" onchange="javascript:handleSelect(this)">
<option value="home">Home</option>
<option value="contact">Contact</option>
</select>

<script type="text/javascript">
  function handleSelect(elm)
  {
     window.location = elm.value+".php";
  }
</script>

Use a real dropdown menu instead: a list (ul, li) and links. Never misuse form elements as links.

Readers with screen readers usually scan through a automagically generated list of links – the’ll miss these important information. Many keyboard navigation systems (e.g. JAWS, Opera) offer different keyboard shortcuts for links and form elements.

If you still cannot drop the idea of a select don’t use the onchange handler at least. This is a real pain for keyboard users, it makes your third item nearly inaccessible.

The accepted solution looks good, but there is one case it cannot handle:

The "onchange" event will not be triggered when the same option is reselected. So, I came up with the following improvement:

HTML

<select id="sampleSelect" >
  <option value="Home.php">Home</option>
  <option value="Contact.php">Contact</option>
  <option value="Sitemap.php">Sitemap</option>
</select>

jQuery

$("select").click(function() {
  var open = $(this).data("isopen");
  if(open) {
    window.location.href = $(this).val()
  }
  //set isopen to opposite so next time when use clicked select box
  //it wont trigger this event
  $(this).data("isopen", !open);
});

(I don't have enough reputation to comment on toscho's answer.)

I have no experience with screen readers and I'm sure your points are valid.

However as far as using a keyboard to manipulate selects, it is trivial to select any option by using the keyboard:

TAB to the control

SPACE to open the select list

UP or DOWN arrows to scroll to the desired list item

ENTER to select the desired item

Only on ENTER does the onchange or (JQuery .change()) event fire.

While I personally would not use a form control for simple menus, there are many web applications that use form controls to change the presentation of the page (eg., sort order.) These can be implemented either by AJAX to load new content into the page, or, in older implementations, by triggering new page loads, which is essentially a page link.

IMHO these are valid uses of a form control.