Wireless temperature transmitter
If you want to measure temperatures of remote objects there is the only way to do this – get wireless. This particular project explains ho to build simple wireless RF temperature transmitter which uses TXM-433 module and Atmega8 while receiver (SILRX-433) is connected to PC via RS232 port.

RF Temperature transmitter sends six bytes of data at fixed interval. Module measures three temperature values, light level at photocell and battery voltage. Small Visual Basic program collects data and displays it in a table view. As author (Don Carveth ) says – he can monitor temperature and the light went on of three compost heaps in the back yard by sitting in the room. But this is pretty universal device to use it for other purposes. Program code is written for GCC compiler.
[...] RF Temperature transmitter sends six bytes of data at fixed interval. Module measures three temperature values, light level at photocell and battery voltage. Small Visual Basic program collects data and displays it in a table view. As author (Don Carveth ) says – he can monitor temperature and the light went on of three compost heaps in the back yard by sitting in the room. But this is pretty universal device to use it for other purposes. Program code is written for GCC compiler. [via] [...]