Most users know that you can easily create .zip files in OS X by selecting a file in Finder and choosing File » Compress "FileNameHere" or by control+clicking the file and choosing the same option from the context menu. You can open .zip (and other archive formats such as gzip, tar, and bzip2) simply by double clicking on them.
You may not have known that additional options are available. For example, after you make a .zip file, you could have the original files moved to the trash automatically, or you could have all .zip files that you create automatically saved to the same folder.
Similarly, you can have all archive files that you expand open to the same directory as the archive, or have them saved to a specific folder.
The feature that I was looking for was this: after I expand an archive, just move the original file to the trash so I don't have to, because I don't want to keep it.
If the default settings work for you, great! But if you'd like a bit more control, there are two ways to do it. (Note: these system paths are current for Snow Leopard. Previous versions of Mac OS X may be different. See note at bottom of this message.)
1) in Finder, use Go » Go to Folder to navigate to
and look for a file called 'Archives.prefPane'. Double click on it, enter your administrator password, and it will be installed into /Library/PreferencePanes/. (Copying it to ~/Library/PreferencePanes/ does not seem to work. You could probably also make a symbolic link, but really, the easiest way is simply to double click it.)
2) If you do not want to install the preference pane (it will be available to anyone who logs into the machine), you can set the preferences from within 'Archive Utility' itself. Just open the preferences, and you will see a window much like the preference pane shown above.
The trick is that Archive Utility usually only launches as needed, and then quits immediately. If you want to access the preferences, you'll need cat-like reflexes, or simply use Finder's Go ... Go to Folder option to navigate to "/System/Library/CoreServices" and launch it manually (LaunchBar users can also launch it by typing 'archive utility' or you can launch Terminal.app and type "open -a Archive\ Utility" to launch it.)
Being able to "fine tune" my Mac is one of the things I like the most, especially when it helps me keep free of hard drive clutter. I'm not worried about running out of hard drive space, I just try not to keep things I no longer need.
This is an update of a tip that I first learned about on macosxhints.com which is now part of Macworld.com. The tip is now somewhat out of date, but if you are using older versions of Mac OS X you might find the paths you need there.