Interface Builder Library?

Question

Is there a library of additional items which can be imported into Interface Builder, either from Apple, third-party, or open-source projects?
Apple provides all the basic elements, but either I haven't learned how to take full advantage of advanced use of the existing items, or some other common items are missing. I would think with the insurgence of new developers and platforms, specifically the iPhone and Cocoa Touch, there might be additional packages or libraries available.
For instance, I like the revolving picker, but for something a little less flashy, a simple pop-up list similar to a web-based select, would be a great little item, allowing for single or multi-item selections.
I'm sure I'm not the first or only developer interested in being to re-use well crafted elements.
Another example is the info light or info dark UIButton. Since I didn't feel comfortable crafting my own programmatically, I put an info light button in my xib file, and programmatically put an opaque circular graphic right over the info graphic, userInteractionEnabled=NO, and voila, functionally the same, but the screen presence is different.
Having a larger library seems like just the thing.
Are there any out there?

Answer 1

Have you looked over Adding Custom Objects to the Library in the Interface Builder User Guide? That feature doesn't provide everything you're asking for, but it might come in handy.
It might be good to remember that IB doesn't create objects, and the xib file doesn't include instructions on how to create an object. IB just specifies an object which must already be defined somewhere. So any 3rd party icon library would not only need to have an API for IB, it would also need to include a framework or static library to actually create the new objects represented by the icons.
Another point to remember is that the appearance of an object in IB doesn't determine what an object's class will be at runtime. That's determined by the Class you specify in the Identity Inspector. So if you have a custom class in your own library, you can use that class in IB by dragging an "Object" (cube) icon into a window, then setting that icon's identity to the custom class.
Hope some of the above is useful to you!
\- Ray