How to add a top nav bar? I would like to add a Facebook style or StackExchange style top navbar to my site. It should show the username, mini profile pix, userpoints, search box and a few other links.

Is there a module for that?
I don't find any module does that specific purpose of making top bar. 
It is usually done by custom themeing. Basically, you add a new region to your theme. 
For example, You define a new region called "topnav" in .info;  code the markup in template.php and .css files. Then go to block administration page, assign stuffs to the topnav region.