An idea I thought of that would be pretty cool, would be the 12 calendar months, with the current month loaded on the screen. Each month could have a different transparent background with the individual days shown in 7 days by 5 weeks format.
I just tried searching for some examples, but couldn't find anything great. The idea is to have a nice background that you would change once a month, plus it offers some utility. Just hit the Home button to see the current month's calendar.