If you use iCal as your calendar app, you might have noticed that each view (day, week, month) retains its own size. So when you switch from week view to month view, the entire window changes size. If you are like me, you hate this. You may have even tried to get each view to be the same size, switching back and forth, carefully adjusting the sizes. But you would do better to quit iCal, then use a text editor (vi, TextEdit, or something else) to look at ~/Library/Preferences/com.apple.iCal.plist

In this file, you will see lots of stuff, including something like the following:

<key>1-day view window rect</key>
<string>{{15, 33}, {875, 700}}</string>
<key>7-day view window rect</key>
<string>{{15, 33}, {875, 700}}</string>
<key>monthly view window rect</key>
<string>{{15, 33}, {875, 700}}</string>

I copied this out of my iCal.plist, and you'll notice that the numbers are all the same. The number pair "{875, 700}" represents the width and height for each particular view. All you need to do is find each of these entries ("1-day", "7-day", and "monthly") in your own .plist file and set the second pair to be the same thing for all three entries. Save and close the file, relaunch iCal, and all views should now be exactly the same size.