Here’s an even better option than all those mentioned. No one seems to be even aware this program exists, but it is by far the most like Onenote on the Mac and one of the best pieces of Mac software out there.

It’s called Curio.
http://www.zengobi.com
It’s really worth checking out. Unfortunately, PR isn’t really what the company is best at. But software? Hell yeah.

I love VoodooPad. But I use it quite different than I used OneNote. The automated hyperlinks are great. The full/pro versions support also AppleScript, so there are unlimitted ways to get stuff in or out, if you give some time. You may, if you are a Windows user, also take a look at ZuluPad. It has some similarities.
One little mention, the free version of VoodooPad is not limitted to 15 pages. I believe the demos of the full/pro versions have a page limit.

I agree Circus Ponies’ Notebook 2.1 is a much more powerful tool, I’ve been using it for years. It leverages the Mac’s Services menu so you don’t have to Print to get stuff into it. You just select something (in pretty much any application) and then use the Mac’s Services menu to send the selected stuff to Notebook as stuff, not as a rendered raster. Quite powerful.

And unlike One Note, you can setup quite a few destinations to clip directly to! So you can put the clippings closer to where they belong. I generally have a clipping page setup for each project I’m active on and as I find things in stream of web mode I clip them directly into the correct project notebook.

Here is a more capible note program for mac.

http://www.circusponies.com/

It looks like a notebook and you can put moies, photos, and other clips into the folder. It keep your thoughts organized.

Does it have any integration with OneNote format?? That’d be great, I’d share a lot of data between the Q1 and the MacBook ;)