I love the "To Do Bar" in Outlook 2007 but it has two major issues.
Number One:
It will only show you items from your Default calendar.
If you have links to Internet calendars/exchange/seperate home and work calendars you will only ever see items from the default 
Number Two:
It does not display calendar items that are all day events!!!
You can see some comments about this in this MSDN blog.
Basically their argument is the to-do bar shows upcoming appointments not upcoming events!?!
This is a slightly contradictory view to the old-fashioned "Outlook Today" page in your inbox. This shows both of the calendar items and distinguishes between them by colour.
This limits the usefulness of the to-do bar as you still need to dip into the full calendar section of outlook just for quick reference.
Take a look at the MSDN blog to see other peoples niggles,like if you hover over a bold date in the navigator it should show you the events/appointments in a screen tip instead of nothing.
Hopefully they will fix this with an add-in or service pack rather than Outlook 2009
>>> On the left is a picture I mocked up of a slightly improved "To-Do Bar". Bear in mind that my paint.net skills aren’t what they should be and it would hopefully look a lot nicer if Microsoft ever chose to implement it. Any changes that are made should have the option of turning them on or off in the to-do bar options.
Petition – Hopefully, if enough people complain then MS will do something about it. As well as commenting
on the MSDN blog why not join this facebook group – Fix Outlook To-Do bar. Also, if you are a beta tester for the next Office version then make sure you tell them what we want!
Workaround
Instead of creating a calendar item as an all day event you would need to set a start time of 00:00 and an end time of 23:59. However this will then fill up your whole day in the calendar view and conflict with any other appointments.
While I am complaining about it …
- it would be nice to have a digital clock and today’s date at the very top, about the same size as an appointment, similar to a gadget from the vista sidebar. I know it is highlighted on the date navigator and also on the system tray but that isn’t obvious enough for me
- It would also be great to get this bar to undock or float on top of other windows in a semi-transparent style.
