Max Kiesler has put together a nice collection of AJAX widgets that he has found during his travels. The reason I find the post so interesting is because he has provided links to each item in his list. This allows a developer to download the widget in question, see a demonstration of it in use, and read documentation needed to implement it on your own. I find that interesting cause I need things spelled out pretty plainly or reusing any sort of widget is too difficult for me to try. :-)

Check it out.