There is a great way to see upcoming appointments at a glance while in any folder in Outlook. In a few simple steps you can turn on and use your To-Do bar. This video is specific to Outlook 2010.
You can change the time increments shown in your Outlook calendar to allow for smaller more detailed calendar entries. This will work in Outlook 2003, Outlook 2007, and Outlook 2010.
Creating a shortcut to open an email pre-addressed to your email address will allow you to quickly take notes or create a reminder to yourself. This will work with Outlook 2003, Outlook 2007, and Outlook 2010.