Here's a very small hint on how to get a cleaner calendar display (without vertical scrollbars) in iCal when displaying all-day events.
One thing that always bugged me about iCal, from 1.0 until now in 1.5.1, was its logic of displaying hours of a day in the daily and weekly views. You can set the preferences to display a day from 8AM to midnight, and to display 16 hours at a time, meaning you see the full day without having to scroll - perfect so far.
Now, as soon as you add an all-day event, only approximately 15.5 hours fit into the view and a scrollbar appears - incredibly stupid. Even though there would be an easy workaround, namely to display more hours in a day, these choices are greyed out in the preferences panel. That's what brought me to look at the app's defaults via the command line.
The simple trick is to use the defaults command to set more hours than necessary, depending on the number concurrent of all-day events you usually have in one display. Just try higher values than you can set up in the preferences by opening a Terminal window and typing:
defaults write com.apple.ical "number of hours displayed" XX
Replace XX with the actual number of new hours you wish to see. For my setup, using 19 hours usually gives me a perfect weekly display.
[robg adds: This is a great little hint! The scroll bars on all-day events have bugged me, too, and I couldn't think of a good way around them -- I also find it odd that resizing the window resizes the existing hours instead of showing more hours.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20031020173314746