I had a look at Circus Ponies Notebook, read a review here
and even downloaded the demo version of the Mac App. I don't think this app is for me. It has a lot of things that I don't need, and I am afraid that the interface will be a hindrance for simple and quick note typing. In fact the review says it is comparable to Pages rather than to other note-taking apps. But for people who are trying to organize and index a lot of documents and material, it looks like an interesting app. Not cheap though, it's a shame they don't have a free evaluation version on the app store.