If you manually manage your iPod, you can still use it for skipping songs in playlists and shuffle play in iTunes, at least, but I'm not sure about on the iPod... I use it for sync'ing my iPod with a library too big to fit on it. 😱
If you do decide to use it, it's also useful to know that option-clicking a checkbox (I think it's option, but it might be another modifier key like ctrl or something) will select or deselect all the songs currently in the browse view. So you can very quickly check/uncheck a genre or songs that meet search criteria or an album or so on. 🙂