For years I used PicturePop which was a contextual menu item just like QuickLook and did virtually the same thing except it didn't play mp3s or movies. I also use Shomi which does play movies and shows folders of images all at once. Apple apparently is making life tough for the PicturePop maker as his Pro version will probably not be doing very well with QuickLook part of the OS now.
QUOTE
i need to think about the concept of PPP to be complementary to QuickLook, and usable in 10.4. The first step will be to have a test of 10.5 and QuickLook/CoverFlow before conitnuing active development of PPP, because i don't want to spend time for nothing...
http://setnan.org/mac/picturepoppro/
http://www.goat.demon.co.uk/shomi.html