noty is a jQuery plugin for creating user-friendly, "JavaScript-alert alternative" notifications very easily.
It has built-in support for alert, success, error and confirmation messagesand they can either be displayed as HTML elements that fade in/out or as modal boxes.
The notifications can be displayed on any part of a web page (top, bottom, center, top left or top right) and many options exist for customization (speed of open/close animations, display duration, being closeable or not and more).
Each notification is displayed from a queue in an order which is nice for making sure each item is shown.
There are various callbacks provided and an online editor exists for customizing the notifications.