I am an avid user on Microsoft OneNote, in my opinion one of the most valuable applications available. I don't know how I could do what I do without it. I also carry a Palm Treo 700W, which runs Windows Mobile 5.0. I just upgraded to the OneNote 2007 beta and it has a very cool OneNote mobile application.
The application allows me to capture richly formated notes, pictures, and audio notes. I am a big believer in the Getting Things Done philosophy and I probably make 20-30 voice notes a day. Sometimes these are actions I have promised, other times just ideas of concepts I want to capture. It also allows me to bi-directionally sync notes will my Tablet. When you sync, it automatically puts the notes in a Mobile notebook and allows me to add additional text.
The way I use it is that I capture 90% of my notes using the voice recording. When I have a moment, I will put a text name and sometimes specific next steps to the note. I then sync the file. Since my 700W has EVDO, I often do this wirelessly and even with the audio file, this works fine. It syncs with a shared notebook that my assistant and I both have access to. She will then transcribe the notes and mark them as Outlook tasks. This will then automatically sync with Outlook and when I complete the tasks in Outlook, it automatically marks it as complete in OneNote.
Here are some other tricks that I use: