OneNote SP1 - now with an API
Microsoft has a preview of OneNote SP1 available. It's got a lot of new features, including better Tablet PC support and better integration with Office. Sounds like Microsoft has really been listening to user feedback to make OneNote better. If you like OneNote as much as I do, download it and check it out.
The most important new feature (to me at least) is tucked at the bottom of the features page “Simple application programming interface (API) for extending OneNote”. I know numerous people have come up with things they would like to use OneNote for (blogging), and it sounds like some of them might be possible now. I plan on playing with the API a little tonight to see what it's all about.