TabletPC and OneNote
The first time I saw OneNote during Beta 1 of Office 2003 I knew it was a winner. So much so that I actually bought a Tablet PC to take full advantage of the paper notepad like experience.
Now that Office 2003 has shipped, I am still using OneNote to track information from everything related to my work and personal life. Even so, it is still a version 1.0 product and has many shortcomings.
Ben Schorr has done a nice job catching numerous frequently asked questions online at his website. If your new to OneNote this is a good place to start.