Customization of those four buttons

If you would prefer to use different buttons to other applications than phone, web, e-mail, and applications here is how to modify that original set:
1. click on the Applications button
2. click on the Menu button
3. View Type, and choose "Customizable Grid"
4. click on the Menu button again and choose "Edit"
5. Now, long-press any of those bottom four app shortcuts and drag them off the bar. Now you have an open slot for another of your favorite four. Okay, really, it is only your favorite three because, the "Applications" button is static. In the Firmware version I am using now, 2.3.3, there is not yet a way to take that button off the Main Menu.