I see this a lot on flickr and other sites, and was wondering if anyone knew of a script out there that can use the same functionality.

Usually it is a pop-in box that appears over the current page or sometimes just a div box with a small X to close it out. I would like to have a box with warnings that users can click on once to disable once they read the message. Then when ever I need it to be seen again, it will pop up until they again click the X to disable it. I hope I explained my self correctly. Anyway, thanks for the help.