noty is a jQuery plugin that makes it easy to create alert - success - error - warning - information - b messages as an alternative the standard alert dialog. Each notification is added to a queue. (Optional)
The notifications can be positioned at the; top - topLeft - topCenter - topRight - center - centerLeft - centerRight - bottom - bottomLeft - bottomCenter - bottomRight
There are lots of other options in the API to customise the text, animation, speed, buttons and much more.
It also has various callbacks for the buttons, opening closing the notifications and queue control.
Documentation and examples are here: http://needim.github.com/noty