I’m not sure how much you’ve played with Quicklook in Leopard, but it changes the way I work in some pretty substantial ways. Previewing stills or music files go so much quicker. Select multiple files and you can bring up a really cool Index Sheet.
Another really cool part is that Apple allows people to create plugins for Quicklook. There are a few sites on the web to get plugins. Apple’s own site & QuickLook Plugins List are two good places to start.
That’s BetterZip above & Folder List QuickLook below