A jQuery plugin that turns a bootstrap dropdown component into a compact multi-select button input that yields selected values as a hidden input with a urlencoded JSON array as its value.
<link rel="stylesheet" href="https://33d73a22f4b6dc792776-9396d99e5006374ffc15abe9d6ae8e26.ssl.cf1.rackcdn.com/dropdownCheckboxes-cdn.min.css">
<script src="https://33d73a22f4b6dc792776-9396d99e5006374ffc15abe9d6ae8e26.ssl.cf1.rackcdn.com/dropdownCheckboxes.min.js"></script>
$('.mything').dropdownCheckboxes();
All of the config is in the markup. See the example for details.