There is some kind of screen-saver interface that you can use to make a Win32 program play nicely as a screen saver, but I don't know details.

A long time ago, After Dark had a development kit.

Re a framechat screensaver: Use the "channel" screen saver, or that concept. I'm not familiar with channels, but it looks like it displays a web page full-screen.

Animated camel walking across the screen. Pearls. Larry Wall quotes. Shoot-a-monk autoplay. CPAN module summaries. All of the above, mixed together.