Ice Monitors are volunteers who "work the gate" to the ice surfaces. They check-in skaters for practice and warmup sessions, then allow one skater at a time to compete based on the skate order. If someone is missing, they help locate the skater and/or confirm if they've scratched from the event.
At our rink, I also think of them as "gatekeepers." They control access to the ice by opening/closing the rink access door. That way, only one skater is performing at a time and isn't interrupted by someone getting on in error.
It's actually my favorite volunteer role because you get to see everything up close. I keep tissues, sanitizer, safety pins and a first-aid kit handy, just in case skaters need some assistance.
The only part I dislike is that coaches constantly come up and ask "are we running on time?" "What event are we up to?" While it's important for them to know, it's distracting and time-consuming when you have to get the door open for the finished skater and put the next skater on the ice.