I have a "Best" playlist for each genre. Like best rock, where the only criteria is Genre is Rock and Rating is 4 or 5 stars.
I also have an Added Recently, with just lists the 30 most recently imported songs. I have a "Not Rated" smart playlist so I can go through those and continue to rate all my songs. The other one I use a lot is "Rarely Played" which is songs that have been played less than 5 times so I can go through and listen to those songs that get buried on the iPod.