another vote for headsets.
Track map with corner numbers in a handout, as well as instructor area. Folks new to a track won't have the corner numbers memorized, so it's important to give them a reference.
At track lunch options, if the track doesn't have it's own snackbar. Something that doesn't take a ton of time.
More work for the instructors, but written feedback sometime after the event is a great follow up feature and very valuable.
Rentable hero cams or similar. You could probably charge $25 a day use. They'd be paid off in 4 days, the rest is gravy. Bring your own memory card(or purchase at a small profit from cart).
Pictures and or video. People want to show their buddies what they did over the weekend. They don't always have someone that is taking pictures for them(or of them).
I do like that the bmw club offers a first timer discount. First timers have instructors all day, no exceptions. In return they get a 50% discount on their first day.
Lastly, have some roving ambassador types. Every club has those gregarious nice guys that everybody likes. Send them roving around the pits welcoming the new folks and help them with their questions.
Most of these are geared towards folks new to hpde.
