SweetDropdown is a jQuery plugin to create dropdowns in any direction with any kind of content.
vDrop is a minimalistic and customisable jQuery plugin to replace standard HTML select dropdowns.
Pretty Dropdowns is a simple, lightweight jQuery plugin that converts
<select> drop-down menus into "pretty" menus that you can style using CSS. As an extra bonus, it does its best to keep the menu options within the viewport.
A morphing dropdown that animates according to the size of its content by using css and jQuery as seen on stripe.com website.
A tutorial about creating card deck style dropdown by using CSS3 transitions and jQuery.
Nice Select is a lightweight jQuery plugin that replaces native select elements with customizable dropdowns.
Dropy is a simple dropdown created by using SCSS and jQuery.
DropKick.js is a jQuery plugin for creating beautiful, graceful, and painless custom dropdowns.
EasyDropDown is a jQuery plugin that effortlessly turns humble
<select> elements into styleable drop-down menus for use in forms or general UI/navigation.
Selectric is a jQuery plugin designed to help at stylizing and manipulating HTML selects.
A tutorial on how to create some nice custom drop-down lists with CSS and jQuery.
There are five examples with different looking drop-down menus and lists for various purposes.