BMW ZHP Registry Site
From the site's front page:
"Welcome to ZHPRegistry.net - a website for ZHP enthusiasts by ZHP enthusiasts. Our mission is simple: register as many ZHPs as possible to get a better understanding of the population size and breakdown by various options. Submitted VINs are not associated with your personal information, including e-mail address. Please read our privacy policy for more information."
I like the idea of not having to provide personal information. Fact is, I think many people refrain from participating in registries when they have to provide too much identifying information. I believe ZHPRegistry.net's approach will be perfect.