One sweet, low-cost Valentine's Day gift idea is to make a playlist or mix CD for your significant other, and these often include some sentimental, inside reference-type songs — your first dance song at your wedding, the song playing in the background when you first met, songs by a band you saw together in concert, or, say, a song the cab driver blasted in Las Vegas so you could dance around in the backseat. You know — the songs that make people squeal "It's our song!" when they come on in public places. Do you have "a song" with your significant other? If so, what is it?