Is there a good video to screensaver converter for Mac?

I had a good screensaver maker in Windows and I miss being able to convert my videos to screensavers. Is there a good (preferrably free) application for Mac that will allow me to do the same thing? It'd be great if there was one that can allow me to work with .avi, .mov, .mp4, etc. type files. I don't really want to have to work with .swf files.