I highly recommend PepeSoft's Calendar+
You can download it here:
http://www.mohairsofa.com/
It allows you to select how many days you want displayed, and in what format you want it displayed in. Very useful if you have multiple appointments each day.
Also, check out some of deichenlaub's other suggestions. I use Pocket Informant and it works very well, a good replacement for the unfortunately useless Pocket Outlook.
The URLs are:
Pocket Informant -
http://www.pocketinformant.com/
Agenda Fusion -
http://www.agendafusion.com/
HTH,
Nick