I'm not sure if others already know this about iTunes--I didn't until tonight. As my iTunes library grows, I've accumulated several versions of many songs that I like--studio version, multiple live versions, "covers"--each a bit different, etc. Often, when I find a different version (usually a different live version or a cover) of a song, I want to replace an older version of the same song that I may have buried in more than one playlist. I can't always remember which playlists I've put them in. (I have many "compilation" playlists.)
Until tonight, I didn't know that if you highlight a song in your iTunes library and "control-click" on it, among the many options you'll get is to "show in playlist." Select that option and you'll see which playlists you've placed that particular version in. Makes replacing a song very easy.
