qTip. Advanced tooltip plugin for jQuery, including borders and pointers created using CSS. Very flexible (we used this for the latest MP expenses application) but a little on the heavy side, weighing in at 38KB when minified. # 6:23 pm
tipsy. Simple Facebook-style tooltip plugin for jQuery. # 6:21 pm
jsondns. A JSONP API for making DNS queries, with a nice URL structure. # 5:37 pm