For me, QuickLook is one of the killer new features in Leopard. QuickLook allows you to select any file (or folder) in the finder, hit the space bar, and get a usable preview of that file without opening it.
I think QuickLook is pretty awesome right out of the box, but today it got a whole lot more useful, thanks to Japanese developer, Taiyo.
Taiyo developed a free QuickLook plugin that allows you to view the contents of a zip archive, instead of just the icon (the default behavior for zip files in QuickLook).
I’ve always been annoyed that in the default installation of OSX, there is no way of seeing what’s in a zip without extracting everything. That’s just stupid! I’ve tried other shareware apps that claim the ability to browse zip archives without opening them, but they either didn’t work, or didn’t work very well. Thank you Taiyo!
One note… I’ve read that for some people the plugin kicked in immediately after installation. I personally needed to logout for it to start working. You could also just force-quite the finder.
Taiyo also developed a QuickLook plugin for folders, which shows the contents of folders, instead of their icon. If you spend most of you time in either list or icon view, this could be very handy too.