Change Hidden iTunes Preferences is an application that will let you invoke some so-called "hidden" iTunes preferences: Show "Library" playlist, Show genre while browsing, Allow half-stars in ratings, Show arrow links -- to either search the iTunes Store or search your library, Load complete iTunes Store preview before playing, Play songs while importing or converting, and Create file names with track number. Some of these preferences, as some users may recognize, used to be available in iTunes' Preferences. Others, like the "Library" and half-stars prefs, have recently been discovered. This is for use with iTunes 8 or better only.
The download disk image contains the actual application (which is not an AppleScript) and an AppleScript to launch the app from your iTunes Script menu. Make sure you copy both of them off the .dmg.