Absolutely painless - Cool Extension. I am using Joomla 1.0.15 and the rhuk template. Only problem is that the rhuk template does not have a user position in the header. Opened a support ticket and got a complete and easy to follow explanation to implement it.

COOL - COOL - COOL - COOL - COOL - COOL

and I didn't have to learn Flash to make it work, it just grabs the images out of a folder on the server. I had fun for hours trying all the built in transitions and overlays.