Yes, I tracked the available 4-digit callsigns for a few weeks. Some local hams grumble about my district 1 callsign, but I did grow up in Boston after all. I wanted to find a 4 digit one with the C and the S together, but that was asking too much. As it was, when I applied, KC1S was on another person's application, but he got his preferred one and that released the callsign for me. My wife settled for N7SJS, the last three match her initials.