Smart Playlist in iTunes for songs that contain lyrics
You can't do this with a smart playlist as Apple doesn't expose the lyric field there.

You can create an Applescript that creates a playlist. You'd then have to rerun the script to update the playlist. A track has a playlist field so you'd just check that.

Here's one example of such a script

tell application "iTunes"

    if exists playlist "No Lyrics" then
        delete playlist "No Lyrics"
    end if

    make new playlist with properties {name:"No Lyrics"}

   duplicate (every track of playlist 1 whose lyrics is equal to "") to playlist "No Lyrics"

end tell