Your favorite iTunes smart playlists

Earlier today I posted my wish for some additional iPod functionality, and TUAW reader Chris Fenison left a comment describing a smart playlist he created that retrieves the music added to his iTunes library within the past few days, so he always has a fresh playlist to listen to. This got me thinking about what other great iTunes smart playlists our readers have come up with. One I consider essential is the one I call "Random," which I use when I want to shuffle all the music on my 'Pod. It's set up to exclude iTrip stations, anything categorized as "children's music" (sorry, kids) and any audiobooks. There's something about the experience of Public Enemy followed by Raffi followed by NPR that I'd rather not repeat.

So what are your favorite smart playlists? Do you have certain smart playlists for certain scenarios (bike riding vs. the commute to work or school)? Share the wealth.