iTunes: songs not in playlist

I have a bunch of songs in the "My iTunes" main music library. I didn't sort all of the songs into various playlists, but I can't remember which ones, and they don't transfer to my iPod. Is there any way to see which songs are not in my playlists?

Also is there a way to prevent duplicates from going into the same playlist? I sometimes discover I drag the same songs into the same playlists.

Thanks

Duplicates problem:

Click EDIT thn click SHOW DUPLICATES.