I was wondering if there are any 3rd party controls for use with the iPhone that are available, even better if usable from Interface Builder. From what I can gather, the answer is no.

I come from a Microsoft .NET background where of course there are tons of controls available from 3rd parties. I'm curious if this is a general Mac development ecosystem fact, i.e. no 3rd party controls for sale, or just an iPhone one, or if I've just missed finding them.