iPhone Status/Overview App Wanted
I'm not aware of any app that does exactly this. The closest I've seen is System Status, which is an Activity Monitor-style app that has a big battery status display, as well as lots of other info on free memory, device space, running processes, etc.

Something that does exactly what you're looking for is unlikely, as there are no public APIs for getting the device signal strength. Any such app wouldn't be allowed in the App Store. It is conceivable you could make something for a jailbroken device.

Perhaps just position the phone closer on your desk, as all that information is readily available in the standard iOS status bar.