Today Plug-in:

Tabs. Battery, backlight, memory indicators, drag-and-drop, ...

File Explorer:

ZIP support, encryption, "Folder Up" button, storage card format, file properties, ...

Close Button:

The close (X) button really closes programs, task manager, ...

Pocket Internet Explorer:

Multiple windows, full screen mode, save as, view source, ...

Buttons:

Alt-Tab, backlight change using a button, keyboard navigation in the Today plug-in, ...

Safe Mode:

Loading the device in safe mode to prevent it from hard-reset in case of any problems.

Other:

Taskbar battery indicator, extended Pocket PC themes, plug-ins, ...