I have had three seperate experiences with empty flights.

1) Right after 9/11 I was on a WN flight from SAN to PHX and I was 1 of 2 pax on the plane. Very cool since there were more FAs than pax.

2) Just recently I was coming home from YYC to DFW. It was right before Christmas and Y may have been 25% full, but there were just 2 of us in F.

3) Coming back from a SFO MR about two weeks ago there were a total of 18 people on the plane. 9 in Y and 9 in F. We were so light my upgrade almost didn't clear because of weight & balance restrictions. They needed more bodies in the back to balance the plane. It was on a new 738 with the sky interior. FA and I spent the last 20 minutes of the flight playing with all of the cool colors you can make the cabin. That is a COOL plane.