[Mattinblack]

I played with this last year. In Javascript you can create a whole page section that looks like a pop-up complete with all the chrome but is positioned off the screen. You can then move it instantly onto the screen, it can have anything in it that a webpage can.

Because it was loaded with the web page the blockers cant block it. If you want to be nasty and antisocial you can make it follow the mouse and cover each thumbnail till the user clicks on it to make it go away, linking to a new window with a further site in a frame with code that sends it to the back - a pop-under. Because this resulted from a user request (a vanilla mouse click with no javascript) the blockers wont catch that either!