Tool tips with Mootools just got even more cooler! Check it out, its called Smart Hover Box. You can add a hover html elements to any other element by adding a single id.

Smart Hover Box Features:

• create a hover box out of any html element
• smart positioning will always show hover box in window quadrant with the most space
• optional close button by adding a user defined class to any element
• user defined x and y hover element offset
• user defined timeout after mouseleave event

Link: http://www.consideropen.com/blog/2008/08/smart-hover-box-for-mootools-12/