Here's the deal. I'm wanting to add a pop-up window to my site advertising my newsletter and giving visitors the option to sign up to it. Getting the pop-up window to work is no problem and I can do that.
The thing is, having a pop-up window appear everything to visit a site is going to be annoying, so what I want this window to do is set a cookie on the user's machine saying that they've seen this pop-up window.
Then, when the user comes back, the front page will detect the cookie on their machine and not show them the pop up window because they've already seen it and the cookie has been set. Does that make sense?
Any help and some examples would be greatly appreciated.
Checkout these threads for information on the popup SitePoint uses, which should fit your needs:
Hope that helps. :)