Just like in Microsoft Excel, you can automatically resize the a column in iTunes by double-clicking the divider line on the right (as in 'not left') side of the column you want to resize. The column will then resize to the width of the largest item in it, including the column's title.
This is great for saving space, or for quickly seeing all of a particularly long song or album title.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050810175646312