BigClock is a simple application through the iSpazio source that displays a digital clock on your iPhone’s screen. The clock uses the entire screen. All you have to do is open the application and it will load the clock. I’m not sure what you would use this for on a daily bases however, I could see using it when we record our video podcasts so that we know how long we have been talking for!! Let me know in the comments what you might use this application for!
Update: There was a quick update to version 1.1.1 of BigClock. With the update, you are able to double-tap on the time to change it to military time. You can then double-tap again to change it back to standard time.