At long last, my PowerToy is live! Send to OneNote from Outlook lets you send Mail, Post items and Sticky Notes to OneNote (note, this was previously called Outlook2OneNote).
While you are there I also recommend Send to OneNote from Internet Explorer.
Both of these use the OneNoteImporter that Donovan created.
A lot of folks at Microsoft were instrumental in dogfooding the product as well as answering my never ending questions about managed programmability in Office 2003. Special thanks to Siew Moi Khor and Misha Shneerson for showing me the light.
Note, if you install this PowerToy and you do not see the toolbar icons in your Outlook standard toolbar this is because the Outlook 2003 .NET Programmability Support is not enabled. To fix this you must: