If you ever want to select all but one playlist (or movie, podcast, app, etc.) to sync in your iPod or iPhone's iTunes dashboard, it seems you have to select every single one manually.

It turns out there's an easier way: just Option-click on any entry in the list. This will toggle the state of all items in the list between 'selected' and 'not selected.' Then you can just change the few you don't want (or do want), and sync.