What about also adding a Travel Insurance add on, along with some other sports? I'm going snowboarding next week and am getting annual worldwide travel insurance policy for myself and the missus through AA. It's pretty affordable and covers Kitesurfing, snowboarding, Diving and surfing (which we do) and a whole bunch of other stuff which we do not do. It doesn't cover 3rd party liability - as the IKSA policy does. You'd drive a bunch of kiters onto the IKSA if you rebranded and sold such a policy.
Once you have the higher subs, then maybe a monthly newsletter. One thing I'd like to see more of is a Calendar of Events well in advance. Annual leave is tight, but there are a bunch of events around the country that typically don't move whether the wind is blowing or not. A lot of us desk jockies end up having our Calendars booked out months if not the whole year in advance with family/holiday/other events. It would be great to know the kiting events that far in advance so I could reserve them properly.
Intermediates are also crying out for Clinics to bring on their skills. Sometimes the schools organise these. The IKSA would do really well to present a school with a group (or a number of groups) of 4-6 willing intermediates and then maybe organise accomodation around it. Biggest problem for intermediates is getting a group of similar level people they can chat to off the water and then be able to push each other on the water. IKSA is made for building those social bonds. Small groups is the key!