OrigamiCar announced a nice application for UMPCs (it will be useful for Tablets too i believe) :
Taskswitcher.
What is TaskSwitcher?
TaskSwitcher is a small application specifically written for UMPC touchscreen computers that gives you instant access to various useful functions that are otherwise a little more tricky on a computer without a keyboard.
When it is running, a small gray panel appears at the top center of the screen on your UMPC. Tapping this panel allows you to cycle through your open programs.
Read the full blog entry.