Here's something I stumbled on. Not a big hint, but maybe useful for some:
To Expand/Contract all Podcasts in your Podcast playlist: Command-Click the dropdown triangle next to a podcast.
[robg adds: This hint also stated that Option-clicking the dropdown triangle next to a podcast would retrieve the full episode list. In my testing, it didn't do anything like that; it worked just like clicking a triangle (i.e. the entry for the clicked-upon triangle expands).]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050628164701696