$.fn.betterTooltip = function(options){
	
	/* Setup the options for the tooltip that can be 
	   accessed from outside the plugin              */
	var defaults = {
		speed: 200,
		delay: 300
	};
	
	var options = $.extend(defaults, options);
	
	/* Create a function that builds the tooltip 
	   markup. Then, prepend the tooltip to the body */
	getTip = function() {
		var tTip = 
			"<div class='tip'>" +
				"<div class='tipMid'>"	+
				"</div>" +
				"<div class='tipBtm'></div>" +
			"</div>";
		return tTip;
	}
	$("body").prepend(getTip());
	
	/* Give each item with the class associated with 
	   the plugin the ability to call the tooltip    */
	$(this).each(function(){
		
		var $this = $(this);
		var tip = $('.tip');
		var tipInner = $('.tip .tipMid');
		
		var tTitle = (this.title);
		this.title = "";
		
		
		/* Mouse over and out functions*/
		$this.hover(
			function() {
				/* so we can calculate correct position even on resize / change of tab */
				var tWidth = $this.width();
				var tHeight = $this.height();
				var offset = $(this).offset();
				var tLeft = offset.left + (tWidth/2);
				var tTop = offset.top;
				tipInner.html(tTitle);
				setTip(tTop, tLeft);
				setTimer();
			}, 
			function() {
				stopTimer();
				tip.hide();
			}
		);		   
		
		/* Delay the fade-in animation of the tooltip */
		setTimer = function() {
			$this.showTipTimer = setInterval("showTip()", defaults.delay);
		}
		
		stopTimer = function() {
			clearInterval($this.showTipTimer);
		}
		
		/* Position the tooltip relative to the class 
		   associated with the tooltip                */
		setTip = function(top, left){
			var topOffset = tip.height();
			var xTip = (left-20)+"px";
			var yTip = (top-topOffset-35)+"px";		
			tip.css({'top' : yTip, 'left' : xTip});
		}
		
		/* This function stops the timer and creates the
		   fade-in animation                          */
		showTip = function(){
			stopTimer();
			tip.animate({"top": "+=20px", "opacity": "toggle"}, defaults.speed);
		}
	});
};

http://net.tutsplus.com/tutorials/javascript-ajax/build-a-better-tooltip-with-jquery-awesomeness/

Also includes the fix for when the user resizes the window.

Jquery Easy Tooltip Generator

javascript, jquery

jQuery