Dan, over at JWSecure has written a bunch of new samples for some difficult to use API's ( previously he also wrote some cred prov samples )

The new batch includes a CNG plugin to implement a new cipher algorithm in Vista - cool stuff. I especially liked his section on 'kicking the tires' and a little about his methodolgy behind new API's.

 http://jwsecure.com/dan/2007/05/now_available_new_vista_securi.html

spatdsg