Wouldn't it be great if Mac OS X's Quick Look would let you inspect the contents of compressed archives? With the help of the BetterZip Quick Look Generator, it can.
The currently supported archive formats are: ZIP, TAR, GZip, BZip2, ARJ, LZH, ISO, CHM, CAB, CPIO, RAR, 7-Zip, DEB, RPM, StuffIt's SIT, DiskDoubler, BinHex, and MacBinary.
Download it here, unpack, and copy the BetterZipQL.qlgenerator bundle to your /Library/QuickLook folder (if you want to install it for all users on your Mac) or to the ~/Library/QuickLook folder, this is the Library/QuickLook folder inside your user folder. You may need to create the QuickLook folder inside ~/Library first.
The Quick Look framework will need a little time before it realizes that a new generator has been added. If you are impatient and not afraid of using the terminal, you can execute the following command to make the Quick Look framework reset immediately:
> qlmanage -r
or you could restart the Finder. Or logout and -in again. Or restart your Mac. Or take a nap. You choose.
You can set the various options directly in the Quick Look pop-up. Just click the Preferences button in the upper right area. Set your options and click the button again to hide it.