We decided to build a weather station for my son's bedroom.  Outside, we will have sensors and a short-range radio, powered by battery.  Outside sensors will include temperature and humidity.

Inside, the display console will have a radio receiver, barometric pressure sensor, temperature sensor, and a display.

The display will show the various readings, possibly some trends as well.

The display will run on an Arduino and use a 4-line, 20 character display.