Addicted to OneNote
Can't live without OneNote anymore. It's such a nice tool, simple and right to the point.
If you use it and haven't installed the SP1 preview, I strongly suggest you do so. Lots of nice features were added. One of mine favorite is adding Outlook meetings details. You can find it here: http://www.microsoft.com/office/onenote/prodinfo/sp1/default.mspx