Tiki has a built-in class (called tikihelp) that allows you to create a formatted tooltip for a link as follows:
The following syntax:
{HTML()}<a href="HomePage" class="tikihelp" title="Home Page: This links to the home page for this site">Home Page</a>{HTML}
Would produce on this site:
Home Page
Mouse over the above link to see the formatted tooltip. Here's what's important for the tooltip to appear like this:
Wiki-Syntax Links