FancyForm is a powerful checkbox replacement script used to provide the ultimate flexibility in changing the appearance and function of HTML form elements. It’s accessible, easy to use and degrades gracefully on all older, non-supporting browsers.
Milkbox is an amazing lightbox script which is easy to implement and can be used for photo galleries, videos, etc…
Quickboxes allows you to check multiple checkboxes in one mouse click and drag
SmoothScroll allows the page to animate down to an anchor within the page instead of the ugly jump that occurs by default.
This allows you to control how tooltips display so make them creative.
ZebraTables is an easy to implement MooTools class that provides alternate-row-coloring support, hover highlighting, and click coloring.