[danik.js]

Открой для себя setTimeout ))

<script>
function setIncrementalInterval(callback, startInterval, increment) {
	var timeout = startInterval;
	(function fn() {
		setTimeout(function(){
			callback();
			timeout += increment;
			fn();
		}, timeout);
	})();
}

var lastTime;
var fn = function(){
	var now = new Date();
	var interval = now - lastTime;
	document.body.innerHTML += interval + '<br />';
	lastTime = now;
};

lastTime = new Date();
setIncrementalInterval(fn, 1000, 100);

</script>