The library I hear the most about is jQuery. However there are a whole lot more. Developers sometimes think that ExtJS does not get enough press.
If you are not integrating it into a commercial product, you can get ExtJS for free. You add some lines of code to your header section to bring in the ExtJS functionality. Then you use the extension library framework.
Teamwork Challenges - One of the newer guys on the team asked our project manager for some info. He needed to figure out how to get his scripts logging in to run unattended. Th...