Attention Box

Attention Box is a simple and lightweight jQuery plugin that helps push important messages onto the screen and your users. Its subtle and beautiful see-through background makes it blend into any design. It also can take user inputs along with other features listed below and includes a very easy to follow documentation on the demo page.

Very easy to integrate
Lightweight jQuery plugin
Smooth transitions
Responds to Escape key for cancelling message
Automatic reposition upon window resize or scroll
Can take user inputs
Can be configured to require user input
Can be configured to have different modal overlay colors
Can display error message for input boxes

UPDATE – 8/6/2010:

Fixed a reported bug where the message would disappear from the screen