App Name: My GoodTime
My GoodTime allows you to have an advanced digital clock without purchasing it!
All you need to do is to download this app and you can change your iDevice into a digital clock.
You can add alarms with a lot of different ringtones to choose from
It also shows you the day of the week, the date, so it pretty much has the calender function as well.
With different background designs, you can also choose the one that's most suitable for you
Requires iOS 4.3 or later
iTunes Store Link: App Store - My GoodTime