Have you seen the nice javascript windows in the sitepoint market place?

Pop unders i think they are called.

Basically i need to launch some content in a new window, but dont want to use the old fashioned window.open (a new browser window), and i dont want to use the horrible alert() either.

I want it like in the sitepoint market place where a new window opens in the current window and allows you to make bids etc.

Please provide me with the javascript and HTML, and tell me how i can change the text in that window whenever it needs. Like by calling a function etc.

the more simple the JS the better.

PS: I know AJAX quite well - so im more of an advanced noob