In rinks with only skill-level classes-"Free Style 5" "Freeskate 4"- you'll start seeing class enrollment drop off, as kids get bored or discouraged. A synchro program can help, although at least one local director thinks that Synchro teams run by municipal programs (as opposed to club-run) are problematic at best, and program-killing at worst.
Specialty classes, on the other hand, give kids a reason to skate, and can reward their strengths, instead of feeling like punishment for not measuring up.
For one thing, they aren't in any "curriculum" so you get to tailor them to your program. Have a lot of competitive kids? Take a page from USFS and do "media training" to teach kids (and parents) about how to promote themselves, and about responsible use of social media in a "professional" context. Or run "competition class" where kids act as judges, with training in ISI and ISU judging protocols.
If you have a lot of delusional kids, who think they're better than they are, rather than constantly berating them, have a choreography class, or junior coaching, or Moves.
Are you primarily recreational? Want to lure your regular public session people into more classes? How about Ice Games (races, rotation Olympics, or whatever you can some up with). Take a look at ISI competition categories, even if you're a Basic Skills rink. ISI has tons of marvelously creative categories-Couples, Family, Rhythmic, Team-that would be fantastic as a class (and might boost your rink's participation in ISI events).
I've always liked the idea of a permanent "clinics" class in the curriculum--three week classes that you can do a la carte (at a premium) or in a sets of three for a regular class rate. You could do these mini-sessions in Spins, Intro to Jumps, Choreo, doubles or triples, Axel or double axel, whatever you want. A class slot devoted to specialty clinics can help your coaches, as well, allowing them to sign on to present whatever their specialty is.
Specialty classes don't have to be on-ice, either. Keep people in your facility by offering them in sets-- practice ice/levels class/specialty class/off-ice class marathons, with a price break, to keep people in your facility. Throw in discount coupons for your pro shop or concession stand for people who sign up for this. Off-ice can be traditional conditioning-/dance-based classes including aerobics, or dance, or yoga, or pilates, but they can also be informational, like the above-suggested Media class, or training in judging protocols (parents would take this one, I bet), or "draw" class, where you learn about the marks that jumps, spins and moves make on the ice (literally, you draw them. I love draw class).
A lot of programs have Power and Jump classes, but too often these are just the levels classes with a different name. Your specialty classes should be just that--special.
Rotate the coaches through the classes. This is a great way to help younger coaches, by giving them the opportunity to really shine in something they're good at. Too many rinks never alter the schedule--they have Coach Seniority teaching FS6 on Tuesdays at 6 for 20 years; who cares if everyone hates Coach Seniority and only his students sign up for class.
To get the classes going, pair them with the rest of the program--a discount certainly, or some sort of cumulative benefit for taking multiple classes--ribbons, "skater of the month" awards, etc. Give friend-discounts for bringing new people into the program. Give it some time as well; at least 3 sessions so it can catch on.
Remember the statistics- there are 500 elite skaters nationwide, and I hate to break it to you, but they aren't at your rink. Rinks need to stop running programs as though everyone is the Broadmoor, and start serving the tens of thousands of committed recreational and workaday competitors who just love to skate.
What unusual specialty classes does your program, rink, or club offer?