jQuery multiselect drop down menu

Question

I have a simple html multi select drop down list:

<select id="transactionType" multiple="multiple" size="10">
  <option value="ALLOC">ALLOC</option>
  <option value="LOAD1">LOAD1</option>
  <option value="LOAD2">LOAD2</option>
  <!-- etcetera... -->
</select>

I want to continue to use this list in the event javascript is disabled however with javaScript I would like to render the list as a multi-select drop down list. That is it only shows one item in the list until clicked and then will expand to show x items and provide scrolling, where I can select multiple elements as you would expect while holding shift or ctrl.

New to jQuery was searching the http://jquery.com/ but haven't yet found what I need.

Edit Struts2 users, the selected answer will url encode with [] this causes issues in struts2 the fix however is very easy. Simply open jquery.multiSelect.js and search for "[]" and delete the one instance this is used in a string concatenation. I also am using jQuery 1.4.4 as opposed to the 1.3.2 which came bundled with it and everything works just fine.