I guess there are other options, but the IKO offers kiteboarder insurance, damn high deductible though. (Gettin' ripped there!)

The IKO insurance covers you during your private practice. It covers Bodily injury or Property damage caused by a member while participating in the sport of Kiteboarding, Snowkiting or Powerkiting.
It covers $1.000.000 Bodily Injury and Property Damage per Occurrence, $1.000 Deductible for General Liability and $10.000 / 25.000 for Accident / Medical.

89 US / 68 Euros including USA/Canada (excluding local taxes).
65 US / 49 Euros excluding USA/Canada (excluding local taxes).

http://www.ikointl.com/kiteboarder-insurance.php

Has anyone ever had to claim against either of those?

Even car insurance has "cheaper options", but cost (up or down) does not necessarily relate to their willingness to pay up when you claim

It's hard enough getting insurance companies to pay up after car accident or if your house has been burgled when YOU'RE IN THE RIGHT! Buckley's of a payout after a "Kiting Accident"! I'd be very wary of paying insurance to any organisation who claim they can cover you for your participation in an extreme sport. There's way too much red tape and fine print that insurance companies could use in this case to get out of a potential payout and don't think for one moment that they wouldn't try every trick in the book!!.......you'd be just throwing away your cash for FALSE peace of mind.

I'm with Tbaggn I would love to know if anyone has been able to make a claim in any of the above mentioned.