Personal Data Storage FULL

[rwc7]

I own a Samsung Galaxy P1000, and have recently been getting the Warning Notification that my "Personal Data Storage" is nearly full. I have learned that my device has 81.26MB available for 'Personal Data' storage and that I have used 69.57MB. The Warning Notification suggests that I delete some of the content in order to free up some of the storage space. What is stored in the "Personal Data Storage" and how do I clear it?