Question: Is there any opensource samples of JQuery usages of StackOverFlow-like sites...... 

Any help in this direction??

Answer: 
You can make the same effects by using [plugins](http://plugins.jquery.com/).

* <http://www.jqueryplugins.com/>
* <http://www.sastgroup.com/jquery/240-plugins-jquery>
It could help if everybody would just make a list of the plugins that are being used. For example, for plotting they use: [flot](http://code.google.com/p/flot/). For flot support on IE you need [excanvas](http://excanvas.sourceforge.net/)... I kind of feel this question has been answered before though...