I need an AJAX cart like these below: Is there a project or something that already integrated a cart similar to:

http://interface.eyecon.ro/demos/cart.html

or an integration of jcart:

http://conceptlogic.com/jcart/

I tried ubercart but despite the fact is an overkill it doesn't work like these.
Well, you didn't write the required version. I found a module Ecwid shopping cart. This module has drag and drop features for items and ajax support everywhere. 

For more information, have a look at Ecwid Demo.