Obligatory warning: This script has been designated as a "Retro Script" and there is no guarantee that it will function as described with modern versions of iTunes and OS X and may even corrupt or destroy data.
iTunes will stop updating a podcast if you have not listened to at least one of its episodes in five days. This script will batch-update every podcast subscription so you don't have to manually update each one individually.
I have posted instructions on how to create a launchd agent to run this script automatically and invisibly in the background to ensure that your Podcasts are always updated.
Possible iTunes bug (July 17, 2014): Looks like the iTunes AppleScript command updatePodcast command is broken as of iTunes 11.
Exports and then re-imports selected tracks' artwork
Batch set new Last Played/Last Skipped of selected tracks
Prefix each selected track's Song Name with the number of its order in the selection.
Change the label color of the files of the selected tracks
Export Playlist names of selected Source to text file
Play through each track in a playlist at your set interval