This following code allows them to click a link that says "Add my site to your favorites!"

This code automatically asks your visitor if they want to add your site to their favorites, once the page loads.
<body onLoad="if(document.all) window.external.AddFavorite(window.document.location,window.document.title)">

This code will ask your visitor if they would like to make your website their homepage.
<A HREF="#" onClick="this.style.behavior='url(#default#homepage)'; this.setHomePage('http://www.daydreamed.org');"> Make Daydreamed Your Homepage </A>