Displaying your Desktop over iChat AV

I came across an utility/driver/hack last year that let you choose your
graphics card as your Firewire camera in iChat. That is, instead of
seeing your face, the other side saw what you were demonstrating on
your computer. I think it required you to install iChatUSBCam but I'm
not clear on that.

I've done a bunch of google searching and cannot find this utility.
If anyone knows what I'm talking about, can you please give me a
pointer?

Thanks.