简化了ajax/json功能的jQuery版本

I like AJAX/JSON features of jQuery but the library is very big for blackberry phone development. Has anyone pulled out or developed a stand alone AJAX/JSON library similar to jQuery's? I know that a mobile version of jQuery is coming, but this looks like it is more directed at GUI for iPhone. I also tried XUI, but have been getting JavaScript errors when running in IE7. I like AJAX/JSON features of jQuery but the lib