[http://2tbsp.com/node/100](http://2tbsp.com/node/100) suggests using google trends to judge popularity of ajax libraries; looking at the current data, it looks like jQuery is the clear winner so far in the AJAX library stakes. The current trends can be found [here](http://trends.google.com/websites?q=dojotoolkit.org%2C+jquery.com%2C+prototypejs.org%2C+mootools.net%2C+http%3A%2F%2Fdeveloper.yahoo.com%2Fyui%2F&geo=all&date=all&sort=2)